longitudinally discontinuous channel-floodplain divided by either water storage areas or housing/farming banks diminishes the floodplain deposition at the discontinuous locations. The present numerical experiments do not show an obvious peak discharge increase, nonetheless, the recognized erosion-deposition characteristics would help further study of the floodplain effects on the peak of hyperconcentrated floods.","Hyperconcentrated flood;; floodplain effects; channel-floodplain system; coupled morphodynamic model; peak discharge; Yellow River","en","journal article","","","","","","","","2019-06-01","","","Environmental Fluid Mechanics","","","" "uuid:5ba8b9a0-a273-4b15-aa15-86383932c8ae","http://resolver.tudelft.nl/uuid:5ba8b9a0-a273-4b15-aa15-86383932c8ae","A stochastic model approach for optimisation of lowland river restoration works","van Vuren, B.G. (TU Delft Hydraulic Structures and Flood Risk; HKV Consultants); de Vriend, H.J. (TU Delft Rivers, Ports, Waterways and Dredging Engineering); Barneveld, Hermjan (HKV Consultants)","","2016","Over the course of centuries, river systems have been heavily trained for the purpose of safe discharge of water, sediment and ice, and improves navigation. Traditionally, dikes are used to be reinforced and heightened to protect countries from ever higher flood levels. Other types of solutions than technical engineering solutions, such as measures to increase the flood conveyance capacity (e.g., lowering of groynes and floodplains, setting back dikes) become more popular. These solutions may however increase the river bed dynamics and thus impact negatively navigation, maintenance dredging and flood safety. A variety of numerical models are available to predict the impact of river restoration works on river processes. Often little attention is paid to the assessment of uncertainties. In this paper, we show how we can make uncertainty explicit using a stochastic approach. This approach helps identifying uncertainty sources and assessing their contribution to the overall uncertainty in river processes. The approach gives engineers a better understanding of system behaviour and enables them to intervene with the river system, so as to avoid undesired situations. We illustrate the merits of this stochastic approach for optimising lowland river restoration works in the Rhine in the Netherlands.","dredging; flood protection; navigation; river restoration; Room for the River program; stochastic approach","en","journal article","","","","","","","","","","","Hydraulic Structures and Flood Risk","","","" "uuid:b34ba88d-842f-4691-85fb-b738ea107b65","http://resolver.tudelft.nl/uuid:b34ba88d-842f-4691-85fb-b738ea107b65","Do intertidal flats ever reach equilibrium?","Maan, D.C.; van Prooijen, B.C.; Wang, Z.B.; de Vriend, H.J.","","2015","Various studies have identified a strong relation between the hydrodynamic forces and the equilibrium profile for intertidal flats. A thorough understanding of the interplay between the hydrodynamic forces and the morphology, however, concerns more than the equilibrium state alone. We study the basic processes and feedback mechanisms underlying the long-term behavior of the intertidal system, restricting ourselves to unvegetated intertidal flats that are controlled by cross-shore tidal currents and wind waves and applying a 1-D cross-shore morphodynamic model. The results indicate that by an adjustment of the profile slope and shape, an initial imbalance between deposition and erosion is minimized within a few decades. What follows is a state of long-term seaward progradation or landward retreat of the intertidal flat, in which the cross-shore profile shape is largely maintained and the imbalance between deposition and erosion is not further reduced. These long-term trends can be explained by positive feedbacks from the morphology onto the hydrodynamic forces over the flat: initial accretion (erosion) decreases (increases) the shear stresses over the flat, which induces further accretion (erosion). This implies that a static equilibrium state cannot exist; the flat either builds out or retreats. The modeled behavior is in accordance with observations in the Yangtze Estuary. To treat these unbalanced systems with a one-dimensional numerical model, we propose a moving (Lagrangian) framework in which a stable cross-sectional shape and progradation speed can be derived for growing tidal flats, as a function of the wave climate and the sediment concentration in deeper water.","","en","journal article","American Geophysical Union (AGU)","","","","","","","2016-05-30","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:09326701-94ee-4493-8c5a-2d96f9abc300","http://resolver.tudelft.nl/uuid:09326701-94ee-4493-8c5a-2d96f9abc300","The long-term response of rivers to engineering works and climate change","De Vriend, H.J.","","2015","Rivers respond to changes in their geometry or their controls in various ways and at a wide range of space and time scales. The response consists of changes in properties such as cross-sectional shape and area, slope, planform pattern, bed roughness and bed sediment composition. Usually, attention for the morphological impact of engineering works focuses on short-term effects. The usually much slower, but also much more persistent large-scale response is often ignored, or countermeasures are ineffective. In many cases this has led to extra maintenance costs, in some even to hazardous situations or disaster. This paper refreshes and extends long-existing but seemingly forgotten knowledge on large-scale river behaviour. It gives examples of impacts of engineering works, climate change and sea level rise, discusses potential countermeasures and gives a number of general conclusions on the large-scale morphological behaviour of lowland rivers.","floods & floodworks; hydraulics & hydrodynamics; river engineering","en","journal article","ICE Publishing","","","","","","","2016-06-17","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:7a605793-b09e-439a-ac11-a03690d241ab","http://resolver.tudelft.nl/uuid:7a605793-b09e-439a-ac11-a03690d241ab","Relative role of bed roughness change and bed erosion on peak discharge increase in hyperconcentrated floods","Li, W.; Wang, Z.B.; Van Maren, D.S.; De Vriend, H.J.; Wu, B.S.","","2014","River floods are usually featured by a downstream flattening discharge peak whereas a downstream increasing discharge peak is observed at a rate exceeding the tributary discharge during highly silt-laden floods (hyperconcentrated floods) in China’s Yellow River. It entails a great challenge in the downstream flood defence and the underlying mechanisms need to be unravelled. Previous study on this issue only focuses on one possible mechanism, while the present work aims to reveal the relative importance of bed roughness change and bed erosion in the hyperconcentrated flood. Using a newly developed fully coupled morphodynamic model, we have conducted a numerical study for the 2004 hyperconcentrated flood in the Xiaolangdi-Jiahetan reach of the Lower Yellow River. In order to focus on the physical mechanism and to reduce uncertainty from low-resolution topography data, the numerical modeling was carried out in a schematized 1-D channel of constant width. The basic understanding that bed roughness decreases with concentration at moderate concentrations (e.g. several 10 s to 100 s g L?1) was incorporated by a simple power-law relation between Manning roughness coefficient and sediment concentration. The feedback between the bed deformation and the turbid flow, however, was fully accounted for, in the constituting equations as well as in the numerical solutions. The model successfully reproduced the downstream flood peak increase for the 2004 flood when considering the hyperconcentration-induced bed roughness reduction. As the hyperconcentration lags shortly behind the flood peak, later parts of the flood wave may experience less friction and overtake the wave front, leading to the discharge increase. In comparison, bed erosion is much less important to the discharge increase, at least for hyperconcentrated flood of moderate sediment concentration.","","en","journal article","European Geosciences Union","","","","","","","","Civil Engineering and Geosciences","Water Management","","","","" "uuid:24937629-1af3-4933-8144-77cb1ef2aa4a","http://resolver.tudelft.nl/uuid:24937629-1af3-4933-8144-77cb1ef2aa4a","'Building with nature': The new Dutch approach to coastal and river works","De Vriend, H.J.; Van Koningsveld, M.; Aarninkhof, S.","","2014","The Netherlands has adopted a new, proactive approach to developing its extensive coastal and river works called ‘building with nature’. Rather than simply minimising or mitigating the environmental impact of harbours, navigation channels, land reclamation and flood defences, the idea is to make use of the dynamics of the natural environment and provide opportunities for natural processes. Existing concepts and ideas have been further developed and tested in a number of full-scale pilot experiments, including sand engines, oyster reefs and waveattenuating forests. This paper describes a number of these experiments along with the preliminary results and lessons learned.","","en","journal article","ICE Publishing","","","","","","","2015-02-28","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:3d12158b-9940-4d69-a870-4311839ed68b","http://resolver.tudelft.nl/uuid:3d12158b-9940-4d69-a870-4311839ed68b","Detailed simulation of morphodynamics: 3. Ripples and dunes","Nabi, M.; De Vriend, H.J.; Mosselman, E.; Sloff, C.J.; Shimizu, Y.","","2013","We present a 3-D physics-based high-resolution modeling approach to the dynamics of underwater ripples and dunes. The flow is modeled by large eddy simulation on a Cartesian grid with local refinements. The sediment transport is modeled by computing pickup, transport over the bed, transport in the water column, and deposition of rigid spherical particles in a Lagrangian framework. The morphological development of the bed is modeled by a sediment balance equation in which the pickup and deposition from the sediment motion submodels appear as source and sink terms. The model realistically replicated the formation and migration of dunes. Model results showed a good agreement with data from five flume experiments. We subsequently applied the model to investigate the effect of sediment grain size on ripples. Finer sediments were found to yield more superimposed ripples than coarser sediments. Moreover, under the same hydrodynamic conditions, the finer sediments yielded two-dimensional bed forms, whereas for coarser sediment irregularities increased. We extended the tests to pronounced 3-D morphologies by simulating the development of local scour at a pier. The results agreed well with experimental data. The model contributes to unraveling the complex problem of small-scale morphodynamics and may be used in a wide range of applications, for instance, to develop more reliable parameterizations of small-scale processes for application in large-scale morphodynamic models.","river morphodynamics; dunes; ripples; sediment transport; large eddy simulation; pier scour","en","journal article","American Geophysical Union","","","","","","","2014-03-20","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:bafec7d8-2c1c-4ee5-85d6-3353397e3fe3","http://resolver.tudelft.nl/uuid:bafec7d8-2c1c-4ee5-85d6-3353397e3fe3","Detailed simulation of morphodynamics: 2. Sediment pickup, transport, and deposition","Nabi, M.; De Vriend, H.J.; Mosselman, E.; Sloff, C.J.; Shimizu, Y.","","2013","The paper describes a numerical model for simulating sediment transport with eddy-resolving 3-D models. This sediment model consists of four submodels: pickup, transport over the bed, transport in the water column and deposition, all based on a turbulent flow model using large-eddy simulation. The sediment is considered as uniform rigid spherical particles. This is usually a valid assumption for sand-bed rivers where underwater dune formation is most prominent. Under certain shear stress conditions, these particles are picked up from the bed due to an imbalance of gravity and flow forces. They either roll and slide on the bed in a sheet of sediment or separate from the bed and get suspended in the flow. Sooner or later, the suspended particles settle on the bed again. Each of these steps is modeled separately, yielding a physics-based process model for sediment transport, suitable for the simulation of bed morphodynamics. The sediment model is validated with theoretical findings such as the Rouse profile as well as with empirical relations of sediment bed load and suspended load transport. The current model shows good agreement with these theoretical and empirical relations. Moreover, the saltation mechanism is simulated, and the average saltation length, height, and velocity are found to be in good agreement with experimental results.","river morphodynamics; sediment transport; particles; sediment pickup; saltation; large eddy simulation","en","journal article","American Geophysical Union","","","","","","","2014-02-07","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:9a06cb7d-c6fe-41e1-9e05-63d30bce6dbf","http://resolver.tudelft.nl/uuid:9a06cb7d-c6fe-41e1-9e05-63d30bce6dbf","Morphological modeling using a fully coupled, total variation diminishing upwind-biased centered scheme","Li, W.; De Vriend, H.J.; Wang, Z.; Van Maren, D.S.","","2013","High-resolution morphological modeling of fluvial processes with complex, rapidly varying flows has been limited so far by model accuracy or computational efficiency. One of the most widely used numerical algorithms is based on the total variation diminishing method, solved by either upwind or centered approaches. An upwind scheme preserves high accuracy but is complex and computationally demanding, whereas the simplicity and efficiency of a centered approach compromise the accuracy. The present paper extends a recent upwind-biased centered scheme originally developed for clear water and scalar transport over a rigid bed, to sediment-laden flows over an erodible bed. It does so by developing a fully coupled 2-D mathematical model using a finite volume method for structured grids. The complete set of noncapacity-based governing equations, involving the effects of bed deformation and sediment density variation, as well as the influences of turbulence and sediment diffusion, and the temporal and spatial scales needed for sediment adaptation, is solved at one time to obtain synchronous solutions for the entire computational domain. For stability, a two-stage splitting approach together with a second-order Runge-Kutta method is employed for the source terms. The model is verified in a number of tests covering a wide range of complex (sediment-laden) flows. The model is demonstrated to accurately simulate shock waves and reflection waves, but also rapid bed deformations at high sediment transport rates. The combination of high numerical accuracy and computational efficiency makes the model an important tool to forecast flood events in morphologically complex areas.","morphological modeling; coupled solution; upwind-biased centered scheme; finite volume method; sediment transport; erodible bed; dam break","en","journal article","American Geophysical Union","","","","","","","2013-12-20","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:0b67a995-24de-42c4-aa78-252ad2dd458e","http://resolver.tudelft.nl/uuid:0b67a995-24de-42c4-aa78-252ad2dd458e","Meander dynamics: A reduced-order nonlinear model without curvature restrictions for flow and bed morphology","Ottevanger, W.; Blanckaert, K.; Uijttewaal, W.S.J.; De Vriend, H.J.","","2013","Reduced-order models remain essential tools for meander modeling, especially for processes at large length scales and long time scales, probabilistic simulations, rapid assessments, or when input data are scarce or uncertain. Present reduced-order meander models consider their dependent variables either as small-amplitude variations compared to a basic state (linearity) or as varying gradually in a spatial sense (gradual variation). In a prequel, Blanckaert and de Vriend () derived a nonlinear reduced-order hydrodynamic model without curvature restrictions and showed that linearity or gradual curvature variations assumptions do not hold in strongly curved channels. Moreover, in strongly curved channels, a nonlinear feedback mechanism causes the secondary flow strength to be smaller than its linear mild-curvature equivalent. In the limit of mild-amplitude variations and mild curvature, their nonlinear meander flow model simplifies to a well-known linear formulation. The present paper extends this nonlinear modeling to the bed morphology in strongly curved bends, making use of Exner's sediment conservation principle. Furthermore, the model quantifying the relative influence of the downslope gravitational force is refined by considering nonlinear effects. The coupled nonlinear flow and bed morphology model yields satisfactory results for the bed topography, whereas the corresponding linear model strongly overpredicts the magnitude of the transverse bed slope. Analysis of the forcing mechanisms indicate that this erroneous behavior is caused by an overestimation of the upslope drag force due to the secondary flow.","meandering streams; curvature; secondary flow; gravitational pull; nonlinear mechanics","en","journal article","American Geophysical Union","","","","","","","2013-12-10","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:fb8040da-4359-4ea6-9468-30cfd670c542","http://resolver.tudelft.nl/uuid:fb8040da-4359-4ea6-9468-30cfd670c542","Morphodynamic development of the Yangtze and Scheldt Estuaries under influence of human interferences (abstract)","Wang, Z.B.; De Vriend, H.J.; Ding, P.","","2013","","","en","conference paper","IAHR","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:bc6adf64-b2c4-4801-8897-427de21681d8","http://resolver.tudelft.nl/uuid:bc6adf64-b2c4-4801-8897-427de21681d8","Relative role of bed roughness, bed erosion and channel storage on peak discharge increase in hyperconcentrated floods (abstract)","Li, W.; Wang, Z.B.; Van Maren, D.S.; De Vriend, H.J.; Wu, B.S.","","2013","","","en","conference paper","IAHR","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:d6d66593-3f5c-4fec-86b3-2a4287455ba6","http://resolver.tudelft.nl/uuid:d6d66593-3f5c-4fec-86b3-2a4287455ba6","Building with nature: Thinking, acting and interacting differently","De Vriend, H.J.; Van Koningsveld, M.","","2012","","","en","book","Ecoshape","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:e7b9b95c-30ad-44e1-ad3b-50ee058b38be","http://resolver.tudelft.nl/uuid:e7b9b95c-30ad-44e1-ad3b-50ee058b38be","Detailed simulation of morphodynamics: 1. Hydrodynamic model","Nabi, M.; De Vriend, H.J.; Mosselman, E.; Sloff, C.J.; Shimizu, Y.","","2012","We present a three-dimensional high-resolution hydrodynamic model for unsteady incompressible flow over an evolving bed topography. This is achieved by using a multilevel Cartesian grid technique that allows the grid to be refined in high-gradient regions and in the vicinity of the river bed. The grid can be locally refined and adapted to the bed geometry, managing the Cartesian grid cells and faces using a hierarchical tree data approach. A ghost-cell immersed-boundary technique is applied to cells intersecting the bed topography. The governing equations have been discretized using a finite-volume method on a staggered grid, conserving second-order accuracy in time and space. The solution advances in time using the fractional step approach. Large-eddy simulation is used as turbulence closure. We validate the model against several experiments and other results from literature. Model results for Stokes flow around a cylinder in the vicinity of a moving wall agree well with Wannier’s analytical solution. At higher Reynolds numbers, computed trailing bubble length, separation angle, and drag coefficient compare favorably with experimental and previous computational results. Results for the flow over two- and three-dimensional dunes agree well with published data, including a fair reproduction of recirculation zones, horse-shoe structures, and boiling effects. This shows that the model is suitable for being used as a hydrodynamic submodel in the high-resolution modeling of sediment transport and formation and evolution of subaqueous ripples and dunes.","cartesian grid; dunes; large eddy simulation; multigrid; ripples; river morphodynamics","en","journal article","American Geophysical Union","","","","","","","2013-06-20","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:b5bf666a-39f9-4db8-8667-cb987b9096b3","http://resolver.tudelft.nl/uuid:b5bf666a-39f9-4db8-8667-cb987b9096b3","Eco-dynamic development and design tested for coastal management","Van Raalte, G.H.; Van Koningsveld, M.; Fiselier, J.; De Vriend, H.J.; Rijks, D.","","2011","Working in coastal planning is nearly always innovative, since no two coasts are the same. Even if they appear to be physically similar, local conditions and governance settings are usually different, thus requiring a different approach. Each project is unique, which makes coastal projects exciting and diverse.","","en","conference paper","Institute of Civil Engineers","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:f23c1942-2204-46db-b9a5-6d167056af4b","http://resolver.tudelft.nl/uuid:f23c1942-2204-46db-b9a5-6d167056af4b","Eco-morphological problems in the Yangtze estuary and the Western Scheldt","De Vriend, H.J.; Wang, Z.B.; Ysebaert, T.; Herman, P.M.J.; Ding, P.","","2011","This paper compares the Yangtze Estuary in China and the Western Scheldt Estuary in The Netherlands by their morphodynamic and ecological systems, their engineering works and estuarine management issues, and the major challenges in studying them. Physically speaking, the two estuaries are very different. The Yangtze Estuary is much larger and much more influenced by the upstream river than the Western Scheldt. Yet, they also have a number of morphological and ecological features in common. Both estuaries have a multi-channel system and extensive intertidal flats and wetlands with ecologically valuable flora and fauna. These eco-morphological systems are influenced by similar societal developments and human activities. Examples of the latter are engineering works and dredging activities for improving and maintaining the navigation channels, and shoreline management activities including land reclamations and setbacks. The fundamental eco-morphological phenomena that remain to be analysed and understood are the same for the two estuaries and will be discussed in this paper.","eco-geomorphology; human activities; management issues; research problems","en","journal article","Springer/Society of Wetland Scientists","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:de0aba75-dc83-476b-96eb-2a90aa622e21","http://resolver.tudelft.nl/uuid:de0aba75-dc83-476b-96eb-2a90aa622e21","River science in the light of climate change","De Vriend, H.J.","","2011","Climate change and a river’s response to it are likely to be slow processes as compared to the responses to direct human interventions such as engineering works. Therefore, we have to look at timescales of centuries. Such timescales are difficult to be covered by numerical models and, moreover, uncertainties are so large that the degree of detail offered by numerical model simulations hardly pays off in terms of extra information. Therefore, we fall back on simple basic models providing first-order insight into a river’s long-term behaviour. Starting from the basic drivers and controls of large-scale river morphology, we describe longterm changes as can be expected from climate change and long-lasting human interventions.","","en","conference paper","German Federal Institute of Hydrology","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:21fb76c9-930e-473a-a906-013537d5a5c0","http://resolver.tudelft.nl/uuid:21fb76c9-930e-473a-a906-013537d5a5c0","River Engineering","de Vriend, H.J.; Havinga, H.; van Prooijen, B.C.; Visser, P.J.; Wang, Z.B.","","2011","In this syllabus an overview is given of the basic knowledge, which is required to prepare interventions in rivers and to estimate the consequences of these interventions. The utilization of the river for human purposes and the knowledge of hydraulics, sediment transport and morphology will be treated. At the end of this syllabus some practice examples are discussed, of which a few are focused on the Dutch section of the Rhine River.","","en","lecture notes","TU Delft, Department Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:43406474-0a55-496a-82bc-79cad9139d8a","http://resolver.tudelft.nl/uuid:43406474-0a55-496a-82bc-79cad9139d8a","Rivierwaterbouwkunde","de Vriend, H.J.; Havinga, H.; van Prooijen, B.C.; Visser, P.J.; Wang, Z.B.","","2011","Deze syllabus beoogt een overzicht te geven van de basiskennis die nodig is om ingrepen in de rivier voor te bereiden en de gevolgen ervan te kunnen inschatten. Er wordt ingegaan op het gebruik dat de mens maakt van de rivier en op de kennis van de hydraulica, het sedimenttransport en de morfologie. Aan het einde van het dictaat worden praktijkvoorbeelden behandeld, waarvan een aantal is geënt op het Nederlandse deel van de Rijn.","","nl","lecture notes","TU Delft, Department Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:2eb2abd4-af79-467d-8541-6983e1e75ad0","http://resolver.tudelft.nl/uuid:2eb2abd4-af79-467d-8541-6983e1e75ad0","Meander dynamics: A nonlinear model without curvature restrictions for flow in open?channel bends","Blanckaert, K.; De Vriend, H.J.","","2010","Despite the rapid evolution of computational power, simulation of meander dynamics by means of reduced and computationally less expensive models remains practically relevant for investigation of large?scale and long?term processes, probabilistic predictions, or rapid assessments. Existing meander models are invariantly based on the assumptions of mild curvature and slow curvature variations and fail to explain processes in the high?curvature range. This article proposes a nonlinear model for meander hydrodynamics without curvature restrictions. It provides the distribution of the main flow, the magnitude of the secondary flow, the direction of the bed shear stress, and the curvature?induced additional energy losses. It encompasses existing mild curvature models, remains valid for straight flow, and agrees satisfactorily with experimental data from laboratory experiments under conditions that are more demanding than sharp natural river bends. The proposed model reveals the mechanisms that drive the velocity redistribution in meander bends and their dependence on the river's roughness Cf, the flow depth H, the radius of curvature R, the width B, and bathymetric variations. It identifies Cf?1H/R as the major control parameter for meander hydrodynamics in general and the relative curvature R/B for sharp curvature effects. Both parameters are small in mildly curved bends but O(1) in sharply curved bends, resulting in significant differences in the flow dynamics. Streamwise curvature variations are negligible in mildly curved bends, but they are the major mechanisms for velocity redistribution in sharp bends. Nonlinear feedback between the main and secondary flow also plays a dominant role in sharp bends: it increases energy losses and reduces the secondary flow, the transverse bed slope, and the velocity redistribution.","meander; hydrodynamics; secondary flow","en","journal article","American Geophysical Union","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:db31899c-ca91-47a1-879e-4f4fa1d004e8","http://resolver.tudelft.nl/uuid:db31899c-ca91-47a1-879e-4f4fa1d004e8","A process-based approach to sediment transport in the Yangtze estuary","Chu, A.; Wang, Z.B.; De Vriend, H.J.; Stive, M.J.F.","","2010","A process-based model for the Yangtze Estuary is constructed to study the sediment transport in the estuary. The proposed model covers the entire tidal region of the estuary, the Hangzhou Bay and a large part of the adjacent sea. The dominant processes, fluvial and tidal, are included in the model. The calibration of the model against extensive flow, water level, salinity and suspended sediment data shows a good representation of observed phenomena. With the present calibrated and validated model, the residual flow field and the residual sediment transport field are obtained. The residual sediment transport pattern gives insight into the morphological behaviour of the mouth bars.","Yangtze Estuary; mouth bar; morphology; sediment transport; process-based model","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:4c7f37da-c958-4f4a-a935-43e2651e5c54","http://resolver.tudelft.nl/uuid:4c7f37da-c958-4f4a-a935-43e2651e5c54","Coastal inlets and tidal basins","Stive, M.J.F.; de Vriend, H.J.; Dronkers, J.; van Dongeren, A.; Wang, Z.B.","","2006","","","en","lecture notes","TU Delft, Department Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:52f8854c-d4c3-4426-ba3a-65674d43ec0a","http://resolver.tudelft.nl/uuid:52f8854c-d4c3-4426-ba3a-65674d43ec0a","Rivierwaterbouwkunde","de Vriend, H.J.; Havinga, H.; Visser, P.J.; Wang, Z.B.","","2006","","","nl","lecture notes","TU Delft, Department Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:4555be50-6448-4fe6-85b1-0cac7c261c15","http://resolver.tudelft.nl/uuid:4555be50-6448-4fe6-85b1-0cac7c261c15","Turbulence characteristics in sharp open-channel bends","Blanckaert, K.; De Vriend, H.J.","","2005","In spite of its importance, little is known about the turbulence characteristics in open-channel bends. This paper reports on an experimental investigation of turbulence in one cross section of an open-channel bend. Typical flow features are a bicellular pattern of cross-stream circulation (secondary flow) and a turbulence activity in the outer bend that is significantly less than in the equivalent straight uniform shear flow. Measured distributions are given of the turbulent kinetic energy, its production, the mixing coefficients, some parameters characterizing the turbulence structure, and the fourth-order correlations of the turbulent velocity fluctuations. The transport equation for the turbulent kinetic energy is evaluated term by term, on the basis of the measured data. The results show that the turbulence structure is different from straight uniform flow, in that the Reynolds stress tensor is more diagonally dominant. This is shown to be the main cause of the observed reduction of turbulence activity in the outer bend. The usual two-equation turbulence closure models include a transport equation for the turbulent kinetic energy, but they do not account for this modified turbulence structure. The departures of the measured turbulence structure from its equivalent in straight uniform shear flow are related to a curvature-flux-Richardson number Rf which includes the streamline curvature. Such a relation may be useful to improve simple turbulence closure models for curved open-channel flow.","shear turbulence; channel flow; flow instability; flow simulation; pattern formation; fluctuations; mixing","en","journal article","American Institute of Physics","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:4fb8d283-7df6-4598-a3b9-379e40fd13f4","http://resolver.tudelft.nl/uuid:4fb8d283-7df6-4598-a3b9-379e40fd13f4","Modeling of channel patterns in short tidal basins","Marciano, R.; Wang, Z.B.; Hibma, A.; De Vriend, H.J.; Defina, A.","","2005","We model branching channel patterns in short tidal basins with two methods. A theoretical stability analysis leads to a relationship between the number of channels and physical parameters of the tidal system. The analysis reveals that width and spacing of the channels should decrease as the slope of the bottom profile and the Shields parameter increase and as the mean water depth decreases. In general, the channel depth should halve at every bifurcation. These theoretical results agree well with the field data from the Dutch Wadden Sea. A numerical model based on Delft3D, a software system of WL/Delft Hydraulics, is used to simulate the time evolution of a channel network in a geometrically simplified basin of similar dimensions as the Wadden Sea basins. The resulting channel network displays a three-times branching behavior, similar to the three- to four-times branching patterns observed in the Wadden Sea. The simulated channel pattern satisfies the relation derived from the theoretical analysis. The results of this pattern analysis provide for additional validation of two-dimensional/three-dimensional process-based morphodynamic models of tidal basins.","estuaries; morphology; numerical model","en","journal article","American Geophysical Union","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:e2e56de7-4611-4d9a-9329-383aefe650a1","http://resolver.tudelft.nl/uuid:e2e56de7-4611-4d9a-9329-383aefe650a1","Turbulence structure in sharp open-channel bends","K. Blanckaert, K.; De Vriend, H.J.","","2005","","","en","journal article","Cambridge University Press","","","","","","","","","","","","","" "uuid:c1407273-bb5f-455c-a220-7f2bb7fca870","http://resolver.tudelft.nl/uuid:c1407273-bb5f-455c-a220-7f2bb7fca870","Coastal inlets and Tidal basins","de Vriend, H.J.; Dronkers, J.; Stive, M.J.F.; van Dongeren, A.; Wang, Z.B.","","2005","","","en","lecture notes","TU Delft, Department Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:d223fc62-7fc1-4db8-8c69-1e965f95e59f","http://resolver.tudelft.nl/uuid:d223fc62-7fc1-4db8-8c69-1e965f95e59f","Secondary flow in sharp open-channel bends","Blanckaert, K.; De Vriend, H.J.","","2004","Secondary currents are a characteristic feature of flow in open-channel bends. Besides the classical helical motion (centre-region cell), a weaker and smaller counter-rotating circulation cell (outer-bank cell) is often observed near the outer bank, which is believed to play an important role in bank erosion processes. The mechanisms underlying the circulation cells, especially the outer-bank cell, are still poorly understood, and their numerical simulation still poses problems, not least due to lack of detailed experimental data. The research reported herein provides detailed experimental data on both circulation cells in an open-channel bend such as found in nature. Furthermore, the underlying dynamics are investigated by simultaneously analysing the vorticity equation and the kinetic energy transfer between the mean flow and the turbulence. This shows that turbulence plays a minor role in the generation of the centre-region cell, which is mainly due to the centrifugal force. By accounting for the feedback between the downstream velocity profile and the centre-region cell, a strongly simplified vorticity balance is shown to yield accurate predictions of the velocities in the centre region. For strong curvatures, however, a fully threedimensional flow description is required. Due to the non-monotonic velocity profiles, the centrifugal force favours the outer-bank cell. Moreover, terms related to the anisotropy of the cross-stream turbulence, induced by boundary proximity, are of the same order of magnitude and mainly enhance the outer-bank cell. Both mechanisms strengthen each other. The occurrence of the outer-bank cell is shown to be not just due to flow instability, like in the case of curved laminar flow, but also to kinetic energy input from turbulence.","","en","journal article","Cambridge University Press","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:2e9f2f77-13ba-4c22-9deb-36d33ae32aba","http://resolver.tudelft.nl/uuid:2e9f2f77-13ba-4c22-9deb-36d33ae32aba","Secondary flow in sharp open-channel bends","Blackaert, K.; De Vriend, H.J.","","2004","","","en","journal article","Cambridge University Press","","","","","","","","Civil Engineering and Geosciences","","","","","" "uuid:fc9bcc67-48db-4763-a121-86c7656099e4","http://resolver.tudelft.nl/uuid:fc9bcc67-48db-4763-a121-86c7656099e4","Coastal inlets and tidal basins","De Vriend, H.J.; Dronkers, J.; Stive, M.J.F.; Van Dongeren, A.; Wang, J.H.","","2002","lecture note: Tidal inlets and their associated basins (lagoons) are a common feature of lowland coasts all around the world. A significant part ofthe world's coastlines is formed by barrier island coasts, and most other tidal coasts are interrupted by estuaries and lagoon inlets. These tidal systems play a crucial role in the sediment budget ofthe coastal zone and thus influence the long-term coastal evolution. From a morphological point of view, tidal inlets form highly dynamical systems, which are interlinked with the adjacent coast and the tidal basin or backbarrier area to which they give access. Often, the natural morphodynamic behaviour interferes with unnatural constraints (e.g. coastal defence works) and with the effects of human utilisation (e.g. sand mining). Estuaries and tidal lagoons attract a variety of human activities, such as navigation, recreation, fishing and aquaculture, economical activity in the border zone, sand mining, land reclamation and in some cases hydrocarbon mining. On the other hand, many estuaries and lagoons form the basis of highly valuable and sometimes unique ecosystems. They function as nursery grounds for many species and as resting and feeding grounds for many others. Hence human activities which affect the properties of such a system, or put the environmental functions otherwise at risk, may have important environmental implications. For the proper management of these systems, it is therefore most important to be able to predict the impacts of such activities. At a larger scale, a deficit of sediment in the backbarrier area, due to sea level rise, for instance, can have major effects on the sediment budget of the coastal zone. The outer deltas of the inlets seem to act as sediment buffers, but the ultimate source of the sediment which goes to the backbarrier area is the coast. Since long-term coastal zone management should include sediment management, the capability to predict the large-scale exchange of sediment is of great importance to ICZM (Integrated Coastal Zone Management). The inlets and their outer deltas play a key role in this exchange. These lectures intend to develop an insight into the physical functioning of coastal inlets and tidal basins, such that possible engineering inten/entions are executed from a sustainable, holistic and integrated management perspective. The emphasis will be on inlet and basin systems which are subject to a mixed tidal and wave forcing, with negligible fresh water runoff, typical examples being the Wadden Sea and the Zeeland inlets and basins. Foreign examples are typically barrier-inlet coasts, such as found abundantly along the east-coast of the USA. This implies that fresh and salt water dynamics are not of strong relevance, and that the morphodynamics of these systems are largely determined by the interaction between the coarser sediment (fine to medium sands) and the tide and wave induced water motions.","tidal inlet; tidal basin; waddenzee; collegediktaat wa5303","en","lecture notes","TU Delft, Section Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:08911ef5-5ee8-4a8b-9432-5a5a5dfaa142","http://resolver.tudelft.nl/uuid:08911ef5-5ee8-4a8b-9432-5a5a5dfaa142","Tidal asymmetry and residual sediment transport in estuaries","Wang, Z.B.; Jeuken, C.; De Vriend, H.J.","Deltares","1999","Theoretical study on tidal asymmetry and application to the Westerschelde estuary.","tidal asymmetry; Westerschelde; tidal cycle; sediment transport; estuary","en","report","Deltares (WL)","","","","","","","","","","","","","" "uuid:ec4f7dd5-7102-4fc6-9a60-c7b86e968cfa","http://resolver.tudelft.nl/uuid:ec4f7dd5-7102-4fc6-9a60-c7b86e968cfa","Rivierwaterbouwkunde","De Vriend, H.J.","Havinga, F.J. (contributor); Havinga, H. (contributor); Visser, P.J. (contributor); Wang, Z.B. (contributor)","1998","","rivieren; riverwaterbouwkunde; inleiding; stationaire stroming; hoogwatergolven; sedimenttransport; suspensietransport; initiële sedimentatie/erosie; variabele afvoer; bochtstroming; samenvloeiingen en splitsingen; gebruik van rivieren; ingrepen in rivieren","nl","lecture notes","TU Delft, Department Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:ce17517f-d9bf-4d65-b1c4-a9435c9e6e8d","http://resolver.tudelft.nl/uuid:ce17517f-d9bf-4d65-b1c4-a9435c9e6e8d","Een kwestie van respect","De Vriend, H.J.","","1997","","Intreerede","nl","public lecture","","","","","","","","","","","","","","" "uuid:9ec3e165-dbbf-4e95-9845-282a5ef1a24c","http://resolver.tudelft.nl/uuid:9ec3e165-dbbf-4e95-9845-282a5ef1a24c","Impact of Climatic Change on NW Mediterranean Deltas","Sánchez-Arcilla, A.; Jímenez, J.A.; Pont, D.; Capobianco, M.; Prat, N.; Provansal, M.; Fraunié, P.; Ruol, P.; Abrami, G.; De Vriend, H.J.; Day, J.W.; Stive, M.J.F.; Jelgersma, S.; Pernetta, J.; Sestini, G.","TU Delft","1997","Summary report of the MedDelt project. This project has studied the impact of climate change on the deltas in the northwestern Mediterranean sea.","climate change; Delta","en","report","Meddelt","","","","","","","","","","","","Meddelt","" "uuid:6a2cf2fd-551d-44d9-8526-52b9bc1957dd","http://resolver.tudelft.nl/uuid:6a2cf2fd-551d-44d9-8526-52b9bc1957dd","Advances in Modelling of Large Scale Coastal Evolution","Stive, M.J.F.; De Vriend, H.J.","","1995","The attention for climate change impact on the world's coastlines has established large scale coastal evolution as a topic of wide interest. Some more recent advances in this field, focusing on the potential of mathematical models for the prediction of large scale coastal evolution, are discussed. The key element in this discussion is reduction: of inputs, models, outputs and measured data.","coastal evolution; coastal model; coastlines","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:15dee5de-dc45-47ce-ba30-242ce06d7165","http://resolver.tudelft.nl/uuid:15dee5de-dc45-47ce-ba30-242ce06d7165","Modeling shoreface profile evolution","Stive, M.J.F.; De Vriend, H.J.","","1995","Current knowledge of hydro-, sediment and morpho-dynamics in the shoreface environment is insufficient to undertake shoreface-profile evolution modelling on the basis of first physical principles. We propose a simple, panel-type model to map observed behaviour. The internal dynamics are determined by slope-dependent, wave-induced cross-shoreface transports, while the external driving factors are lateral sediment supply and sea-level rise. This model concept is tested with reasonable success against the observed behaviour of the Central Holland Coast, considering two hindcast periods, one covering the evolution over the last century, the other the Subboreal/Subatlantic evolution. A limitation of this model is that the cross-shoreface dynamics are solely steered by the variations of shoaling, short waves. Since a variety of other wave and current dynamics may be expected to be present in the coastal boundary layer, it may well be that the effects of the mechanisms and conditions which are not represented are hidden in the coefficients of the sediment-transport formula. This limits the accuracy of the coefficients as used, and our findings should be considered as an-order-of-magnitude estimate only. Indeed, behaviour-oriented modelling implies that generalization of results to arbitrary situations and conditions is not straightforward. Yet, we expect that some of the conclusions are more generally applicable. This concerns the substantiation of the assumption that the upper shoreface responds on a much smaller time scale than the lower shoreface, and the idea that the shoreface profile is not always and everywhere in equilibrium with its forcing. A worthwhile observation from the Holland Coast application is, that the bottom slope effect on the transport is only important at geological time scales. The profile evolution at the engineering time scales (say 10 to lOO years) is effectively quasi-static, in that there is no feedback between the long-term averaged transport and the state of the profile. This implies that at these smaller scales the profile changes can be predicted on the basis of a static sediment balance. This does not mean that the gravitational downslope transport is unimportant as a physical phenomenon in coastal profile evolution: It is only unimportant if a highly aggregated model like this is applied at relatively short time scales.","coastal profile","en","journal article","Elsevier","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:445489c0-e497-46ae-a65f-1cc48290d260","http://resolver.tudelft.nl/uuid:445489c0-e497-46ae-a65f-1cc48290d260","Behaviour-oriented models of shoreface evolution","Stive, M.J.F.; De Vriend, H.J.; Cowell Peter, J.; Niedoroda, A.W.","","1995","","Coastal zones Geomorphology Mathematical models Mapping Climate change Coastal engineering Sediments Hydrodynamics Shoreface Behaviour oriented models Morphological response Large scale coastal behaviour Topography 471.1 (Oceanography General) 481.1.1 (Ge","en","conference paper","ASCE","","","","","","","","","","","","","" "uuid:0d091907-22d3-41d2-b08d-56073ac6ae17","http://resolver.tudelft.nl/uuid:0d091907-22d3-41d2-b08d-56073ac6ae17","Modeling Shoreface Profile Evolution","Stive, M.J.F.; De Vriend, H.J.","","1995","","evolution; sea-level rise; sediment transport; beach equilibrium","en","journal article","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:33afa192-1fdf-4a69-91bd-74f3875da668","http://resolver.tudelft.nl/uuid:33afa192-1fdf-4a69-91bd-74f3875da668","Verification of the shearstress boundary conditions in the undertow problem","Stive, M.J.F.; De Vriend, H.J.","","1994","As part of a revision of the quasi-3D approach for coastal currents, the two-dimensional undertow problem is being restudied. Since the first proposal for approaches in the 1980's progress has been made by several researchers (e.g. Deigaard and Fredsoe, 1989) on the potential importance of contributions neglected initially, such as the time-mean correlation between horizontal and vertical wave-induced velocities. The effects of wave-decay, sloping bottom and oscillatory bottom boundary layer on this term, initially neglected, have now been derived formally and included in the undertow description. Before checking the effects in comparisons with measurements of undertow profiles, it is considered essential to first concentrate on an improved,or at least verified, formulation of the shearstress boundary condition at wave trough level. Since it is momentarily not feasible to make direct measurements of the shear stress condition at wave trough level, only indirect verification is possible e.g. by expressing the shearstress condition in terms of the set-up gradient. Existing small scale laboratory and recently acquired large scale laboratory results provide the set-up gradient data for this approach. The verification leads to theoretical improvements, and provides insight into possible differences between large and small scale situations.","undertow; cross shore current; shear stress","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:7c5255d7-f98a-4d02-9e15-5c71040f1055","http://resolver.tudelft.nl/uuid:7c5255d7-f98a-4d02-9e15-5c71040f1055","Application of a parametric long term model concept to the Delray beach nourishment program","Capobianco, M.; De Vriend, H.J.; Nicholls Robert, J.; Stive, M.J.F.","","1994","","Shore protection Mathematical models Beaches Erosion Forecasting Diffusion Coastal zones Sand Beach nourishment program Parametric long term model Diffusion based model Erosive losses Erosion control 471.3 (Oceanographic Techniques) 921.6 (Numerical Metho","en","conference paper","Ministerio de Educacion y Ciencia (Spain); Office of Naval Research; Generalitat de Catalunya; Japan Society of Civil Engineers; E.T.S. d'Enginyers de Camins; et al","","","","","","","","","","","","","" "uuid:c13a7bff-6ca4-47d7-b590-93fdfe5eee5b","http://resolver.tudelft.nl/uuid:c13a7bff-6ca4-47d7-b590-93fdfe5eee5b","Shear stresses and mean flow in shoaling and breaking waves","Stive, M.J.F.; De Vriend, H.J.","","1994","We investigate the vertical, wave averaged distributions of shear stresses and Eulerian flow in normally incident, shoaling and breaking waves. It is found that shear stresses are solely due to wave amplitude variations, which can be caused by shoaling, boundary layer dissipation and/or breaking wave dissipation. The resulting shear stress and mean flow distributions for these cases are derived, and compared with earlier work. The attractive, now frequently used modelling choice of specifying a shear stress at the mean surface level is discussed in the context of the constituent equations and related boundary conditions and constraints. A derivation of the shear stress at the mean surface level is given both by using the momentum balance and energy balance equations, which is shown to lead to the same result, if the effects of a changing roller are incorporated correctly). Finally, matching solutions for the shoaling and breaking wave cases between the boundary layer and the middle layer for the shear stresses and the wave averaged flow are derived.","shear stress; cross shore current; breaking waves","en","conference paper","ASCE","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:e20c85f6-f1f1-4107-9397-e9227f88388b","http://resolver.tudelft.nl/uuid:e20c85f6-f1f1-4107-9397-e9227f88388b","Long term evolution of coastal morphology and global change","Capobianco, M.; De Vriend, H.J.; Nicholls, R.J.; Stive, M.J.F.","","1993","Long-term prediction of sediment transport and of morphological behaviour in the coastal zone, in response to human interference or to change in environmental conditions (collectively global change) is an increasingly important issue in coastal zone management, especially in relation to the needs for environmentally compatible development. Having in mind those aspects of the response of the coastal system related to long term dynamics of coastal morphology, the paper briefly describes possible approaches to environmental modelling, particularly the modelling of coasts in a typical context of poor experimental information and process knowledge. These approaches will be of help in the impact and vulnerability assessment required for coastal zone management. Reference will mainly be made to long term modelling activities currently performed in the context of the MAST (Marine Science and Technology Program) morphodynamic project on coastal morphology and to possible approaches to ""qualitative"" modelling which may be used to define tendencies of evolution. lt is argued that significant progress in long-term modelling can be made by adopting an appropriate conceptual framework, particularly a top-down approach. This involves formalizing knowledge and experience and integrating data and available models.","climate change; coastal morphology","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:5d81acfe-c735-4a47-b52b-fc18c18a0f96","http://resolver.tudelft.nl/uuid:5d81acfe-c735-4a47-b52b-fc18c18a0f96","Behaviour-Oriented Models Applied to Shoreface Profile Evolution","Capobianco, M.; De Vriend, H.J.; Nicholls, R.J.; Stive, M.J.F.","","1993","A possible approach for the development of simple predictive methods of shoreface profile evolution is described. By application of a detailed process-based, cross-shore morphodynamic model and of some inductive assumptions we build simple descriptions which reproduce possible behaviours of the upper zones of shoreface profile as a function of time. The paper introduces the model concept and describes its application on the base of diffusion-type formulations while distinguishing time scales from seasons, to years and decades. These scales correspond lo bar and berm formation, to the lifetime of profile nourishments, as far as major human induced modifications are concerned, and to the time scales of weather pattern modifications and sea-level rise as far as natural effects are concerned.","shoreline; coastline","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:a45c14e5-05c0-48b3-8fed-2bea3740e69c","http://resolver.tudelft.nl/uuid:a45c14e5-05c0-48b3-8fed-2bea3740e69c","Approaches to long-term modelling of coastal morphology: A review","De Vriend, H.J.; Capobianco, M.; Chesher, T.; De Swart, H.E.; Latteux, B.; Stive, M.J.F.","","1993","","Coastal zones Coastal engineering Beaches Shore protection Hydrodynamics Water waves Morphology Hydraulic models Simulation Coastal area modeling Coastal evolution 407.3 (Coastal Engineering) 471.4 (Seawater, Tides and Waves) 631.2 (Hydrodynamics)","en","journal article","Elsevier","","","","","","","","","","","","","" "uuid:3cf1453e-4e19-468e-b94e-1d9422e1e70b","http://resolver.tudelft.nl/uuid:3cf1453e-4e19-468e-b94e-1d9422e1e70b","Shore nourishment and the active zone: A time scale dependent view","Stive, M.J.F.; De Vriend, H.J.; Nicholls Robert, J.; Capobianco, M.","","1993","","evolution; Shore protection Coastal zones Coastal engineering Sediment transport Water wave effects Beaches shore nourishment Sand shifting Shoal zone Cross shore spreading Closure depth 407.3 (Coastal Engineering) 631.1 (Fluid Flow General) 471.4 (Seawater, Tides a","en","conference paper","","","","","","","","","","","","","","" "uuid:89c53dee-0d9d-4b9e-ab51-78c9ec2d1093","http://resolver.tudelft.nl/uuid:89c53dee-0d9d-4b9e-ab51-78c9ec2d1093","Mathematical Modelling of 3D Coastal Morphology","De Vriend, H.J.","TU Delft","1992","The present lecture deals with models for situations in which the spatial dimensions cannot be separated according to the scales of the morphological processes. Rather common examples of such situations are the morphological evolution near structures (e.g, breakwaters), river outflows, tidal inlets, etc. But also in the absence of such distinct disturbances, the system can be more complex than one might expect at first sight, for instance due to the presence of a rip channel and bar system. After an outline of the basic concepts of various state-of-the-art models which are claimed to describe 3D coastal evolutions, the potentials and shortcomings of the various model types will be discussed and the role of the constituent process models will be considered from a morphological modelling point of view. Subsequently, the methodology and some pitfalls of practical application will be discussed, and, finally, I will identify the principal needs for further research and the approaches which may be taken. In their book entitled 'Nearshore Dynamics and Coastal Processes' (1988), Horikawa and his colleagues give an excellent review of the state of the art in 30 coastal morphological modelling, though with the emphasis on Japan. In this lecture, I will not attempt to redo their work, but I will give some additions and comments, based on my own experience and recent European research. The lecture leads to the conclusion, that significant achievements have been made in the numerical modelling of 3D coastal morphology, but that more research over a wide area is needed to make these models robustly applicable to arbitrary situations. Initial sedimentation/erosion models definitely deserve their place in coastal morphological modelling, though not as a quantitative predictor of morphological evolutions, but rather as a tool for process analysis and orientation. The prediction potential of strictly 2D-horizontal morphodynamic models will probably remain restricted to special classes of problems, and to short-term evolutions. The highest expectations concern quasi-3D models, which include the vertical structure of the water and sediment motion. The first results of the ""empirical emulation"" of such a model by Watanabe and his co-workers are very encouraging. Part of the future research will have to deal with the physical processes which constitute the morphodynamic system. As these can have very complicated interactions in the longer run, especially if the extraneous conditions are stochastic, it is important to have their further investigation defined from a morphodynamic point of view. Another part concerns the 3D morphodynamic process, as such. The present understanding of this process is not good enough to judge the results of 3D coastal evolution models in arbitrary situations. Long-term modelling, at least its physics-based branch, is a new and challenging field, which certainly deserves further exploration. No doubt, this will also he beneficial to medium-term morphodynamics.","morphology; modelling; 3D; coastal; model analysis; ICCE 1992","en","report","ICCE 1992 local organising committee","","","","","","","","","","","","ICCE 1992","" "uuid:6f7b87ef-68a7-4322-bc4d-671d21bea321","http://resolver.tudelft.nl/uuid:6f7b87ef-68a7-4322-bc4d-671d21bea321","Sea-level rise and shore nourishment. A discussion","Stive, M.J.F.; Nicholls Robert, J.; De Vriend, H.J.","","1991","","evolution; Shore protection OCEANOGRAPHY Sea Level Changes COASTAL ENGINEERING Mathematical Models COASTAL ZONES Morphology Shore nourishment conceptual models 407 (Maritime and Port Structures, Rivers and other Waterways) 471 (Marine Science and Oceanography)","en","journal article","","","","","","","","","","","","","","" "uuid:a882eeed-3c73-48c8-b2fb-d68b9f45df29","http://resolver.tudelft.nl/uuid:a882eeed-3c73-48c8-b2fb-d68b9f45df29","The influence on the environment of coastal structures recently built in the Netherlands","Stigter, C.; Verhagen, H.J.; De Vriend, H.J.; Van der Weijde, R.W.; Van Raalten, C.; Loxham, M.","","1990","In the Netherlands today much attention is paid to the effect of coastal structures on the environment. In the past it was usual to quantify the effect of such a structure on its environment solely with the purpose of deciding whether that effect could imply any hazard to the structure itself (or to structures in the neighbourhood). Nowadays environmental impact studies are mainly carried out to see what possible changes the structure may bring about in the integral coastal system. However, changes in the coastal system can only be studied if information is already available regarding that coastal system. Therefore scientists and engineers from various disciplines, such as hydraulic engineering; sedimentology. geology, physical oceanography and marine biology have joined forces to describe and analyze the long·term and large-scale morphological evolution of the Dutch coastal zone as an integrated system.","environmental impact; deltaworks; beach nourishment; dune erosion","en","conference paper","Pergamon - PIANC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:ac1adaff-fa2c-49a7-ae39-109cbcd11868","http://resolver.tudelft.nl/uuid:ac1adaff-fa2c-49a7-ae39-109cbcd11868","Large-Scale Coastal Evolution Concept","Stive, M.J.F.; Roelvink, D.A.; De Vriend, H.J.","","1990","","53 Waterways (CE); CIVIL; Coastal Engineering; Coastal Morphology; Coastal Processes; Estuaries; evolution; netherlands; Sand Transport; Sea Level","en","conference paper","American Society of Civil Engineers","","","","","","","","","","","","","" "uuid:3c0275e7-cde8-46ff-a06c-02e47014e5f4","http://resolver.tudelft.nl/uuid:3c0275e7-cde8-46ff-a06c-02e47014e5f4","Large-scale coastal evolution concept. The Dutch coast. Paper No. 9","Stive, M.J.F.; Roelvink, D.A.; De Vriend, H.J.","","1990","","Coastal zones GEOLOGY Netherlands OCEANOGRAPHY Sea Level Changes FLOW OF WATER Sediment Transport Coastal evolution coastal processes holocene period cross shore flow longshore transport 471 (Marine Science and Oceanography) 481 (Geology and Geophysics) 6; evolution; netherlands","en","conference paper","","","","","","","","","","","","","","" "uuid:d0328d10-b03f-4137-9427-853784dbb55a","http://resolver.tudelft.nl/uuid:d0328d10-b03f-4137-9427-853784dbb55a","Kustverdediging na 1990 (Kustnota 1990): Technisch rapport 19: Innovatie van kustverdediging","De Vriend, H.J.; Roelvink, J.A.","Rijkswaterstaat","1989","Het onderzoek van kustprocessen in het algemeen, alsmede de recente studie van de Nederlandse kust in het kader van de Nota Kustverdediging, hebben tal van nieuwe inzichten opgeleverd in de werking van de zandige Nederlandse kust als morfologisch systeem. In dit rapport worden de verkregen resultaten geintegreerd tot een samenhangend beeld van de werking van dat systeem en de respons ervan op menselijke ingrepen en veranderende exogene condities. Dit beeld wordt vervolgens gebruikt om te komen tot het doel van de studie, een coherente visie op de te volgen taktiek bij de verdediging van de kust via ""zachte"" (d.w.z. in zand uitgevoerde) maatregelen en op de gevolgen van een langdurig volgehouden beleid ten aanzien van supple ties en zandwinning. De studie bestaat uit twee de len, aan te duiden als ""integrerend"" en ""genererend"". In het integrerende deel wordt bestaande kennis bijeengebracht in een systeembeschrijving, d.w.z. in termen van toestandsbeschrijvingen en overdrachtsrelaties voor een stelsel van ruimtelijke elementen dat samen de Nederlandse kust vormt. Naast dit groo ts chal ige s te lsel, dat vooral de langere termijn (dus voornamelijk ""natuurlijke"") ontwikkelingen beschrijft, wordt voor de Hollandse kust een kleinschaliger systeem ontwikkeld, dat in staat is de respons op menselijke ingrepen, zoals zandwinningen of suppleties, weer te geven. Beide systemen maken gebruik van bestaande kennis en werken daardoor, behalve integrerend, ook inventariserend: ze geven een beeld van wat er ""bekend"" is van het systeem en waar de kennis nog lacunes vertoont. In het genererende deel van de studie worden de systemen, als denkmodel of zelfs al in een operationele vorm (als computerprogramma), gebruikt om te komen tot een coherente visie op kustverdediging met ""zachte"" middelen. Dit betreft zowel kustverdedigingstaktieken (""hoe kunnen we een bedreigd stuk kust het best verdedigen?"") als de gevolgen van langdurig volgehouden beleid t.a. v. aktieve (suppleties) en passieve (geen zandwinning) verdediging.","kustverdediging; zandwinnning; zandsuppletie","nl","report","Rijkswaterstaat, RIKZ (Dienst Getijdewateren)","","","","","","","","","","","","Kustnota","" "uuid:21873027-98ea-42eb-afdb-e2fc48271ae3","http://resolver.tudelft.nl/uuid:21873027-98ea-42eb-afdb-e2fc48271ae3","Sediment transport in rivers - report on experimental and theoretical investigations","De Vriend, H.J.; Koch, F.G.","TU Delft","1987","I: Flow of water in a curved open channel with a fixed plane bed II: Flow of water in a curved open channel with a fixed uneven bed III: Accuracy of measurements in a curved open channel In this report the flow of water in a curved open channel, which consists of a38 m long straight section followed by a 90° bend with a radius of 50 m (see Figure 1), has been investigated. The channel cross-section was rectangular with a horizontal concrete bed, a width of 6 m, and a depth of flow of 0.25 m, and measurements were executed at two discharges: 0.610m3 /s and0.305 m3/s (average velocities of about 0.4 m/s and 0.2 m/s respectively). During these experiments the following phenomena were investigated: a. the vertical distribution of the horizontal velocity components (main flow and helical flow) ; b. the horizontal distribution of the total depth-averaged velocity; and c, the horizontal distribution of the water surface elevation. The experimental results have been compared with the results of a mathematical model of flow in curved open channels, developed at the Laboratory of Fluid Mechanics of the Delft University of Technology.The vertical distributions of the main velocity turned out to be highly similar throughout the flow field, the distribution being well described by the logarithmic profile. The helical velocities derived from the measured data were too inaccurate to compare them more than roughly with their theoretical distributions. The point in a cross-section where the observed depth-averaged velocity reaches its maximum lies near the inner wall in the first part of the curve and moving downstream it gradually shifts towards the outer wall. This phenomenon is attributed to the advective influence of the helical flow. As this influence is not accounted for in the present mathematical model, this model does not predict the phenomenon. The water surface configuration agreed reasonably well with the computed configuration.","sediment transport; river flow; river morphology; bed stability","en","report","Delft Hydraulics","","","","","","","","","","","","TOW","" "uuid:b7b0b007-6f03-47ad-9bcd-550c77b131d0","http://resolver.tudelft.nl/uuid:b7b0b007-6f03-47ad-9bcd-550c77b131d0","The Egmond field data and their use for the validation of mathematical models","De Vriend, H.J.; Reinalda, R.; Derks, H.","TU Delft","1987","The 1981 and 1982/1983 field measurement campaigns in the nearshore zone at Egmond, The Netherlands, are outlined and the access to the resulting data sets is indicated. Besides, the use of these data for mathematical model validation is discussed and some general remarks are made on the set-up of synoptic field campaigns to generate data sets for model validation purposes.","nearshore measurements; field data; validation","en","report","Sogreah","","","","","","","","","","","","","" "uuid:d1ef7cdc-4cb6-45b4-9d95-9428cd171d73","http://resolver.tudelft.nl/uuid:d1ef7cdc-4cb6-45b4-9d95-9428cd171d73","Quasi-3D Nearshore Current Modelling: Wave-Induced Secondary Current","Stive, M.J.F.; De Vriend, H.J.","","1987","","63 Mathematics and Computation (CE); Breaking Waves; CIVIL; Hydrodynamics; Littoral Currents; Nearshore Circulation; Surf Zone; Three-dimensional Models","en","conference paper","American Society of Civil Engineers","","","","","","","","","","","","","" "uuid:2d1e13ec-806a-42d8-b69a-098880181e80","http://resolver.tudelft.nl/uuid:2d1e13ec-806a-42d8-b69a-098880181e80","Quasi-3D Modelling of Nearshore Currents","De Vriend, H.J.; Stive, M.J.F.","","1987","","Oceanography COASTAL ZONES FLOW OF WATER Mathematical Models Nearshore currents 471 (Marine Science and Oceanography) 631 (Fluid Flow)","en","journal article","","","","","","","","","","","","","","" "uuid:1f4abe1d-08a2-4327-bd7d-b253fd1f7edf","http://resolver.tudelft.nl/uuid:1f4abe1d-08a2-4327-bd7d-b253fd1f7edf","Directional Nearshore Wave Propagation and Induced Currents","Dingemans, M.W.; Stive, M.J.F.; Bosma, J.; De Vriend, H.J.; Vogel, J.A.","","1986","","Water waves OCEANOGRAPHY Currents MATHEMATICAL MODELS Directional nearshore wave propagation induced currents numerical model 471 (Marine Science and Oceanography) 631 (Fluid Flow) 921 (Applied Mathematics)","en","conference paper","","","","","","","","","","","","","","" "uuid:0ceadc52-90b1-43ef-9ddc-5cabb8ae554c","http://resolver.tudelft.nl/uuid:0ceadc52-90b1-43ef-9ddc-5cabb8ae554c","Main flow velocity in short and sharply curved river bends","De Vriend, H.J.; Geldof, H.J.","","1983","Results of a mathematical model for the depth-averaged main flow velocity in shallow river bends are compared with measurements in two consecutive sharply-curved short bends in the river Dommel, The Netherlands. The computed main velocity distribution agrees rather well with the measured one in the larger part of each bend. Near the bend exits, however, deviations occur which indicate that secondary flow convection should be included in the mathematical model. Also, the present model is used to verify some qualitative explanations for the skewing of the main velocity distribution (towards the inner bank in the first part of a bend, outwards further downstream) and to show the effect of flow stage variations on the streamline pattern.","river hydraulics; meandering; bend flow; bochtstroming","en","report","Delft University of Technology","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:d42e1810-6657-4941-9703-a2c08a6550f1","http://resolver.tudelft.nl/uuid:d42e1810-6657-4941-9703-a2c08a6550f1","Steady flow in shallow channel bends","De Vriend, H.J.","Kalkwijk, J.P.T. (promotor)","1981","Making use of a mathematical model solving the complete NavierStokes equations for steady flow in coiled rectangular pipes, fully-developed laminar flow in shallow curved channels is analysed physically and mathematically. Transverse convection of momentum by the secondary flow is shown to cause important deformations of the main velocity distribution. The model is also used to investigate simplified computation methods for shallow channels. The usual 'shallow water approximation' is shown to fail here, but a method starting from similarity hypotheses for the main and the secondary flow works well. On the basis of this method, a simplified mathematical model of steady turbulent flow in river bends is developed and verified using the results of laboratory experiments and fully three-dimensional flow computations. This model works well for shallow and mildly curved channels, but it shows important shortcomings if the channel is less shallow or sharplier curved.","River bend; river flow; river morphology","en","doctoral thesis","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:b42b7c01-6f50-4ca4-a08c-526dfe594301","http://resolver.tudelft.nl/uuid:b42b7c01-6f50-4ca4-a08c-526dfe594301","Computation of the flow in shallow river bends","Kalkwijk, J.P.T.; De Vriend, H.J.","","1980","The mathematical model presented describes the flow in rivers of which: i the depth is small compared with the width, ii the width is small compared with the radius of curvature, iii the horizontal length scale of the bottom variations is of the order of magnitude of the width. Within these limits, the channel alignment can be arbitrary and it is not necessary that the width is constant. Furthermore, it is assumed that: iv the flow is mainly friction controlled, v the longitudinal component of the velocity is predominant, vi the Froude number is small. The final set of differential equations accounts for the longitudinal convection (Bernoulli effect), the bottom friction, the flow curvature and the transverse convection of momentum by the secondary flow. The numerical integration procedure is straightforward and requires little computation time. Computational results are presented for a large hydraulic model which fulfills the above conditions.","river hydraulics; river bend; bend flow; annular flume","en","report","Delft University of Technology","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:7a35d722-1373-447d-af50-f3aed341c02b","http://resolver.tudelft.nl/uuid:7a35d722-1373-447d-af50-f3aed341c02b","Flow measurements in a curved rectangular channel","De Vriend, H.J.","","1979","This report describes an extensive experiment on steady turbulent flow in a rather sharply curved U-shaped flume with a shallow rectangular cross-section, under almost the same conditions as earlier, less extensive measurements in the same flume. The experiment was carried out as a part of a research project aiming at a mathematical model of the flow in shallow river bends. Extensive measurements of the water level and the magnitude and direction of the horizontal velocity vector in a threedimensional measuring grid are described and the results are analysed in tenns of main and secondary flow.","steady turbulent flow; experiment; curved channel; mathematical model; river bend","en","report","TU Delft, Department of Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:343e27ca-3018-4b98-9315-5b79976fc677","http://resolver.tudelft.nl/uuid:343e27ca-3018-4b98-9315-5b79976fc677","Steady turbulent flow in curved rectangular channels","De Vriend, H.J.","","1979","After the study of fully developed and developing steady laminar flow in curved channels of shallow rectangular wet cross-section (see earlier reports in this series), steady turbulent flow in such channels is investigated as a next step towards a mathematical model of the flow in shallow river bends. A mathematical model is developed for this type of flow, using a turbulence model with a prescribed distribution of the turbulence viscosity and starting from the same similarity hypothesis as in the equivalent laminar flow models. The influence of various characteristics of the turbulence model and the admissability of the most important assumptions underlying the mathematical system that is solved are tested for the flow in a rather sharply curved flume with rather strong effects of curvature. The performance of the model is tested by comparing its results with experimental data from various laboratory flumes. The turbulence model appears to be of great importance to the secondary flow and the related quantities. The similarity hypothesis yields satisfactory results for the main flow, but it needs to be refined for the calculation of the magnitude and the direction of the bed shear stress. The model appears to be applicable to curved channels of not very sharp curvature (i.e. flows with a smallor intermediate equivalent Dean number), although the secondary flow intensity tends to be underestimated.","steady turbulent flow; turbulence; mathematical model; experiments; curved channels","en","report","TU Delft, Department of Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:04151478-cda9-4d81-becf-7836d98340ff","http://resolver.tudelft.nl/uuid:04151478-cda9-4d81-becf-7836d98340ff","Streamline curvature and bed resistance in shallow water flow","De Vriend, H.J.","","1979","The relationship between streamline curvature and bed resistance in shallow water flow with little side constraint, as derived in 1970 by H.J. Schoemaker, is reconsidered. Schoemaker concluded that the bed resistance causes the curvature of a free streamline to grow exponentially with the distance along this streamline, thus giving rise to a destabilizing tendency. The present analysis shows the bed shear stress to act in a stabilizing way and, as far as it is possible to isolate the influence of the bed resistance on the development of streamline curvature, it is shown to be a damping one. In addition, the applicability of the shallow water equations to the sealing of curved alluvial river models is discussed. It is suggested to introduce additional terms into the streamwise momentum equation, accounting for the advective influence of the secondary flow.","streamline curvature; shallow water flow; bed resistance; bed shear stress; curved alluvial river models; shallow water equations; streamwise momentum equation; momentum equation","en","report","TU Delft, Department of Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:9a31228e-a041-4982-a27a-b4f4b8a8e548","http://resolver.tudelft.nl/uuid:9a31228e-a041-4982-a27a-b4f4b8a8e548","Developing laminar flow in curved rectangular channels","De Vriend, H.J.","","1978","As an intermediate step between earlier investigations on fully developed laminar flow in curved channels of shallow rectancular wet cross-section and the mathematical modeling of turbulent flow in river bends, a mathematical model of developing laminar flow in such channels is investigated. The most important assumptions made in addition to those based on the fully developed flow investigations are verified for the flow in a rather sharply curved flume with rather strong effects of curvature. Experimental data on turbulent flow are compared qualitatively with the results of an equivalent laminar flow computation for two different flumes. This comparison shows the measured and the computed depth-averaged main velocity distributions to agree well beyond the first part of the bend, which confirms the presumption that the mechanism of the main velocity redistribution in turbulent flow is essentially the same as in laminar flow.","curved channels; laminar flow; developing flow; experiment","en","report","TU Delft, Department of Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:931e1f20-ec63-4abf-859f-69bcd504fdde","http://resolver.tudelft.nl/uuid:931e1f20-ec63-4abf-859f-69bcd504fdde","Fully developed laminar flow in curved ducts","De Vriend, H.J.","","1978","A mathematical model of steady, fully developed laminar flow in curved ducts is developed and used to derive a simplified computation method to be applied in another mathematical model predicting the flow in river bends. The laminar flow model is verified by comparing its results with analytical, numerical and experimental results reported in the literature. A series of shallow channel computations is made and the results are analysed, both from a mathematical and from a physical point of view. Various simplified computation methods are considered, most of which yield no satisfactory results when the advective influence of the secondary flow on the main velocity is important. Only a method based on similarity approximation sufficiently accurate to be applied further.","laminar flow; developed flow; computation method; mathematical model; river bend; curved duct; flow prediction; modelling; similarity approximation","en","report","TU Delft, Department of Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:882a5589-2bab-4eb2-b8ed-016f272fc8b3","http://resolver.tudelft.nl/uuid:882a5589-2bab-4eb2-b8ed-016f272fc8b3","Numerieke oplossing van een wiskundig model van de stroming in een ondiepe rivierbocht","De Vriend, H.J.","","1976","Dit rapport behandelt de numerieke' oplossing van de over de waterdiepte gemiddelde massa- en impulsiebalansvergelijkingen voor de permanente, turbulente stroming in een ondiepe, bochtige rivier, zoals die zijn afgeleid in ""A mathematical model of steady flow in curved shallow channels"" (ref. 1, zie pag. 4). Het eerste oogmerk hiervan is een beschrijving te geven van de wiskundige en numerieke achtergronden van het rekenprogramma dat voor de oplossing, van dit probleem in het Laboratorium voor Vloeistofmechanica is ontwikkeld. Een dergelijke beschrijving is nodig als besloten wordt het huidige, in PL/1 geschreven rekenprogramma geheel of gedeeltelijk te vertalen, cq. te herschrijven in een meer gangbare taal als FORTRAN. Met het oog hierop zijn twee procedures die van essentieel belang zijn voor de berekening zowel in PL/1 als in FORTRAN in de bijlagen opgenomen. Een tweede doelstelling van dit rapport is een beschrijving te geven van het bestaande PL/1-programma, zodat dit ook door anderen gebruikt en eventueel gewijzigd of uitgebreid kan worden. Het ligt nl. in de bedoeling in het kader van de TOW-werkgroep Sediment transport in rivieren het bestaande wiskundige model uit te breiden met een zandtransportmodel om berekeningen met erodeerbare bodem uit te kunnen voeren. Aan de verdere ontwikkeling van het rekenprogramma daarvoor zal zowel aan de TH Delft (waar PL/1 gebruikt kan worden) als in het Waterloopkundig Laboratorium De Voorst (waar een FORTRAN-programma nodig is) gewerkt worden. Het rapport omvat 10 hoofdstukken, waarvan het eerste de definities van de gebruikte symbolen en het coördinatenstelsel geeft, de beide volgende een herhaling van de in ref. 1 beschreven herleiding van de vergelijkingen en de oplossingsprocedure omvatten en de laatste 7 nadere beschrijvingen van van de verschillende onderdelen van de berekening zijn. Verder zijn er 6 appendices, in de eerste 5 waarvan wordt ingegaan op de belangrijkste procedures van het PL/1-programma, terwijl in de laatste de opbouw van het programma in detail wordt behandeld en een volledige listing wordt gegeven.","numerieke oplossing; stroming; rivierbocht; massa- en impulsiebalansvergelijking; PL/1; FORTRAN; gebruikshandleiding","nl","report","TU Delft, Department of Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:ac4ccf4f-9d1b-4592-9a46-7f17621b4649","http://resolver.tudelft.nl/uuid:ac4ccf4f-9d1b-4592-9a46-7f17621b4649","A mathematical model of steady flow in curved shallow channels","De Vriend, H.J.","","1976","Uitgaande van de Reynoldsvergelijkingen met de bijbehorende randvoorwaarden wordt een vereenvoudigd wiskundig model afgeleid voor ondiepe bochtige rivieren. met als voornaamste uitgangspunten: - de vertikale afgeleiden van de snelheden zijn groot t.o.v. de horizontale - de schuifspanningseffekten overheersen de traagheids- (advectieve) effekten. Dit lijkt juist voor het geval dat de waterdiepte klein is t.o.v. de breedte en de representatieve bochtstraal. terwijl niet te sterke variaties in de geometrie mogen optreden. Het aldus verkregen stelsel differentiaalvergelijkingen met randvoorwaarden is in twee stappen oplosbaar. Eerst wordt (analytisch) de vertikale verdeling van de snelheidscomponenten en de totale druk bepaald. d.w.z. de vorm van de krommen maar nog niet de numerieke waarden. Met gebruikmaking van deze informatie worden vervolgens de vergelijkingen geIntegreerd over de waterdiepte. waarna de over de diepte gemiddelde waarden van snelheden en druk berekend worden door het geintegreerde stelsel numeriek op te lossen. Bij vergelijking van de resultaten met metingen blijkt het gebruikte model goed te voldoen voor wat betreft de verdelingen in de vertikaal. maar minder goed waar het gaat om de verdeling van de gemiddelde grootheden. vooral bij vlakke bodem. Dit is kwalitatief te verklaren uit het feit dat het advectieve effekt van de secundaire stroming op de hoofdstroom en de invloed van de oevers niet in het model zijn opgenomen.","bend flow; river morphology; annular flume; curved channels","en","report","Delft University of Technology","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:b642ba7a-22de-4a7e-b807-bf39a0d69ff5","http://resolver.tudelft.nl/uuid:b642ba7a-22de-4a7e-b807-bf39a0d69ff5","Literatuuroverzicht Bochtstroming","De Vriend, H.J.","","1972","Dit literatuuroverzicht betreft publikaties over de stroming door een bocht in een open kanaal met vaste bodem en een constante, rechthoekige dwarsdoorsnede, waarbij men zich in het bijzonder bezig houdt met de verdeling van de snelheden en de ligging van de waterspiegel. Er is een onderscheid gemaakt tussen publikaties over experimenteel verkregen resultaten (hoofdstuk I) en die over resultaten van theoretische beschouwingen (hoofdstuk II). De bedoeling daarvan is eerst een duidelijk overzicht te geven van de verschijnselen, die zich bij stroming door een bocht voordoen, alsmede van de parameters, die deze verschijnselen beïnvloeden, om daarna na te gaan welke pogingen ondernomen zijn de bochtstroming op grond van theoretische beschouwingen te beschrijven.","bochtstroming; literatuur; theorie","nl","report","TU Delft, Department of Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:1224d600-1cef-4c5c-bd7e-1bc66c1a3b07","http://resolver.tudelft.nl/uuid:1224d600-1cef-4c5c-bd7e-1bc66c1a3b07","Theory of viscous flow in curved shallow channels","De Vriend, H.J.","","1972","The axisymmetrical, viscous flow in curved channels is considered in the case where the hydraulic radius of the cross-section is small with respect to the average radius of curvature of the bend. First Ananyan's theory on this subject is reconsidered, using a regular perturbation method. The results are applied to a specific channel with a shallow rectangular cross-section. This yields solutions for the tangential velocity component, the secondary circulation and the influence of the latter on the former. Second the case of a shallow, rectangular cross-section is treated, using the method of matched asymptotic expansions ..This yields solutions of the velocity components in three separate regions of the cross-section (viz. near each sidewall and near the central axis of the cross-section), which turn out to be sums","viscus flow; river bend; curved channel","en","report","Delft University of Technology","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:3e33e5aa-2cb0-4a79-aa74-b0d11c6f7216","http://resolver.tudelft.nl/uuid:3e33e5aa-2cb0-4a79-aa74-b0d11c6f7216","Laminaire secundaire stroming in een ondiepe, cilindrische bak met om de as draaiend deksel","De Vriend, H.J.","","1971","Het probleem van de stroming in een rivierbocht is door ir. M.B. de Groot geabstraheerd tot het probleem van de stroming in een cilindrische bak met verticale as, afgesloten met een om die as draaiend, vlak deksel. Een nadeel van de bovengenoemde abstractie is, dat men overgaat op een fundamenteel ander aandrijvend mechanisme: de schuifspanning is vrijwel constant over de hoogte; in een open goot loop de schuifspanning lineair van een maximum aan de bodem naar 0 aan het oppervlak. De Groot bestuurde het geval van een turbulente stroming in de bak met een zestal aannamen: 1. Onsamendrukbare vloeistof 2. Newtonse vloeistof 3. Permanente stroming 4. Alle afgeleiden in tangentiële richting zijn 0 5. Zwaartekracht is de enige uitwendige kracht 6. Quasi-isotrope turbulentie Daar een exacte oplossing van de gevonden vergelijkingen niet mogelijk leek, werden deze eerst sterk vereenvoudigd met nog 2 aannamen: 1. Vertikale snelheid << radiale snelheid << tangentiële snelheid 2. Gradiënten van snelheden en turbulente viscositeit in radiale richting zijn veel kleiner dan die in vertikale richting. Deze aannamen gaan niet op voor plaatsen dicht bij de as of cilinderwand. De resultaten van beide turbulente gevallen werden getoetst aan snelheidsmetingen in een experiment. De overeenstemming tussen theorie en experiment bleek zo gering te zijn, dat nadere onderzoekingen gewenst waren. Dit rapport beschrijft deze nadere onderzoekingen. Ze hebben geleid tot een successieve benadering van de oplossing m.b.v. een ""asymptotische methode"". De eerste orde benadering volgens deze methode komt geheel overeen met de oplossing, die De Groot geeft voor de laminaire stroming. De verkregen resultaten zijn ook experimenteel getest. De overeenstemming tussen theorie en experiment is in dit geval aanzienlijk beter, maar de nauwkeurigheid van de waarnemingen is niet voldoende groot om uit de meetresultaten conclusies te kunnen trekken aangaande de hogere orde benaderingen. Tenslotte worden de resultaten van het laminaire onderzoek vergeleken met de resultaten uit de literatuur, die voornamelijk langs de numerieke weg verkregen zijn. Voor grote Reynoldsgetallen vertonen de snelheidsprofielen sterke overeenkomst met die volgens de metingen van De Groot. Ook de benaderingsmethode wordt vergeleken met de in de literatuur toegepaste. Ondanks een ogenschijnlijk verschillende aanpak zijn de resultaten vrijwel steeds identiek aan die volgens de hier toegepaste benadering, waarschijnlijk alleen in dit geval.","turbulentie; laminaire stroming; secundaire stroming; experiment; asymptotisch","nl","report","TU Delft, Department of Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""