document

Stability of block mats under flow conditions

Smyrnis, A. (author)

Block mattresses or block mats are, nowadays, very commonly applied as protection in a large range of applications either against flow or wave loads. Specifically, this large range of applications contains offshore pipeline protection and stabilization, erosion and scour protection, protection of embankments and river banks (slope protection)....

master thesis 2017

document

Efficiency of hanging silt curtains in cross-flow

Radermacher, M. (author), De Wit, L. (author), Uijttewaal, W.S.J. (author), Winterwerp, J.C. (author)

When dredging in sensitive environments, efforts have to be made to limit the free dispersal of suspended fine sediment from the dredging spill. Especially the use of hanging silt curtains as an environmental mitigation measure is widespread. Despite frequent application, their ability to reduce turbidity levels through vertical diversion of...

journal article 2015

document

Effectiveness of a multipurpose artificial underwater structure as a coral reef canopy: Hydrodynamic and ecological connectivity

Kolijn, D.J. (author)

The following research focuses on artificial underwater structures (a.k.a. artificial reefs) in a coral reef environment to mitigate the natural and anthropogenic pressures which reef systems are increasingly facing worldwide. The research question is stated as: “Establishing a method to determine if a multipurpose artificial underwater...

master thesis 2014

document

Modelling Vertical Variation of Turbulent Flow Across a Surf Zone Using SWASH

Zijlema, M. (author)

This paper presents the application of the open source non-hydrostatic wave-flow model SWASH to propagation of irregular waves in a barred surf zone, and the model results are discussed by comparing against an extensive laboratory data set. This study focus not only on wave transformation in the surf zone, but also on the numerical prediction of...

conference paper 2014

document

Incorporation of the effects of accelerating flow in the design of granular bed protections

Steenstra, R.S. (author)

For the design of granular bed protections often a stability parameter is used. The stability parameter represents the forces that are acting on the stones and is used to predict the response of the bed to these forces. Existing parameters are often derived for a limited range of application. When the parameter is used outside this range, the...

master thesis 2014

document

Turbulence in the wake of a roughness patch

Voermans, J.J. (author)

Little research was done in the past concerning the propagation of three dimensional effect in shallow wake flow caused by a roughness patch. Today’s research on related subjects is dominated by emerging obstructions in shallow water where the flow can be assumed as (quasi) two dimensional. However the relevance of a submerged obstruction with...

master thesis 2013

document

A conceptual framework for shear flow–induced erosion of soft cohesive sediment beds

Winterwerp, J.C. (author), Van Kesteren, W.G.M. (author), Van Prooijen, B.C. (author), Jacobs, W. (author)

This paper proposes a conceptual framework for erosion of cohesive sediment beds. We focus on cohesive beds, distinguishing between floc erosion, surface erosion, and mass erosion. By (our) definition, surface erosion is a drained soil mechanical process, whereas mass erosion occurs under undrained conditions. The eroding shear stress is modeled...

journal article 2012

document

Macrophytes in estuarine gradients: Flow through flexible vegetation

Dijkstra, J.T. (author)

Aquatic plants –or macrophytes- are an important part of coastal, estuarine and freshwater ecosystems worldwide, both from an ecological and an engineering viewpoint. Their meadows provide a wide range of ecosystem services: forming a physical protection of the shoreline, enhancing water quality and harbouring many other organisms. Unfortunately...

doctoral thesis 2012

document

Transport of suspended particles in turbulent open channel flows

Breugem, W.A. (author)

Two experiments are performed in order to investigate suspended sediment transport in a turbulent open channel flow. The first experiment used particle image velocimetry (PIV) to measure the fluid velocity with a high spatial resolution, while particle tracking velocimetry (PTV) was used to measure the velocity of individual sediment particles....

doctoral thesis 2012

document

Modeling the interaction between flow and highly flexible aquatic vegetation

Dijkstra, J.T. (author), Uittenbogaard, R.E. (author)

Aquatic vegetation has an important role in estuaries and rivers by acting as bed stabilizer, filter, food source and nursing area. However, macrophyte populations worldwide are under high anthropogenic pressure. Protection and restoration efforts will benefit from more insight into the interaction between vegetation, currents, waves and...

journal article 2010

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Dynamics of shallow lateral shear layers: Experimental study in a river with a sandy bed

Sukhodolov, A.N. (author), Schnauder, I. (author), Uijttewaal, W.S.J. (author)

Shallow lateral shear layers forming between flows with different velocities, though essential for mixing processes in natural streams, have been examined only in laboratory settings using smooth, fixed?bed channels. This paper reports the results of an experimental study of a shear layer in a straight reach of a natural river where the layer,...

journal article 2010

document

Large-eddy simulation of a curved open-channel flow over topography

Van Balen, W. (author), Uijttewaal, W.S.J. (author), Blanckaert, K. (author)

Large-eddy simulation (LES) is performed of a curved open-channel flow over topography based on the laboratory experiment by Blanckaert [“Topographic steering, flow circulation, velocity redistribution and bed topography in sharp meander bends,” Water Resour. Res., doi:10.1029/2009WR008303 (in press)] . In the experiment, the large-scale bed...

journal article 2010

document

Sharp bend flow: Comparison of Delft3D-FLOW with LES and measurements for sharp bends

Van Sabben, A.J. (author)

For a proper management of rivers and river bends in particular, it is important to have good models to predict the flows through bends. It is important that those developed models are well validated with measurements to demonstrate the usefulness of the models. This research is a validation of the Delft3D-FLOW model which is a model that is...

master thesis 2010

document

Cobble Sea Defence: Hydraulic Interface Stability of Sand underlying a Single Filter Layer

Zoon, A. (author)

A cobble sea defence appears to be an easy constructible protection, with relatively low total costs of ownership. Flume tests show that sand under such single layered constructions is stable. However, it is not exactly known how the hydraulic loading of a breaking wave is reducing in the filter. Two datasets containing pressure measurements in...

master thesis 2010

document

Stone stability under decelerating open-channel flow

Hoan, N.T. (author), Booij, R. (author), Hofland, B. (author), Stive, M.J.F. (author), Verhagen, H.J. (author)

The current research is aimed at finding a proper relation between flow forces acting on the bed and the bed response. To this end, experiments were carried out in which both the bed response (quantified by a dimensionless entrainment rate) and the flow field (velocity and turbulence intensity distributions) are measured. The three available...

conference paper 2007

document

Stone stability under non-uniform flow

Hoan, N.T. (author), Booij, R. (author), Hofland, B. (author), Stive, M.J.F. (author), Verhagen, H.J. (author)

The current research is aimed at finding a dimensionless stability parameter for non-uniform flow in which the effect of turbulence is incorporated. To this end, experiments were carried out in which both the bed response (quantified by a dimensionless entrainment rate) and the flow field (velocity and turbulence intensity distributions) are...

conference paper 2007

document

Modelling hydrodynamics in Eelgrass (Zostera Marina)

Dijkstra, J.T. (author), Uittenbogaard, R.E. (author), Stive, M.J.F. (author)

In many areas around the world, there is a large interest in the protection and restoration of aquatic vegetation, like eelgrass (Zostera marina), but little is known about the interaction of such vegetation with its environment. To improve this knowledge, a model has been developed that simulates this interaction between highly flexible...

conference paper 2006

document

A linear approach for the evolution of coherent structures in shallow mixing layers

Van Prooijen, B.C. (author), Uijttewaal, W.S.J. (author)

The development of large coherent structures in a shallow mixing layer is analyzed. The results are validated with experimental data obtained from particle tracking velocimetry. The mean flow field is modeled using the self-similarity of the velocity profiles. The characteristic features of the down-stream development of a shallow mixing layer...

journal article 2002

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Grootschalige horizontale structuren in een rivier met uiterwaarden: Een experimentele studie

Van Prooijen, B.C. (author)

Dit afstudeerwerk bestaat uit het ontwerpen van een fysisch model, het uitvoeren van experimenten, het verwerken van de metingen en het interpreteren van de resultaten. Allereerst wordt in hoofdstuk 2 aan de hand van een probleemanalyse ingegaan op de literatuur betreffende de (ondiepe) menglaagstroming en wordt de doelstelling van het...

master thesis 1999

document

Entraining Flow of a Concentrated Benthic Suspension: Computations with the Prandtl Mixing-Length Model

Kranenburg, C. (author)

The Prandtl mixing-length model of turbulent exchange of mass and momentum is applied to calculate the entrainment of overlying water into a layer of suspended fine sediment at a horizontal bed. In the field the flow and turbulence in such a concentrated benthic suspension (CBS) are driven by a streamwise pressure gradient resulting from the...

report 1999