Searched for: subject:"roughness"
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Khajeh Salehani, M. (author)
The main objective of this thesis is to obtain a better understanding of adhesive contacts and their frictional behaviour. Both natural and man-made surfaces are rough over a wide range of length scales. Tribological studies of rough surfaces need to account for the interactions between these asperities. In this work a sim- ple atomistically...
doctoral thesis 2019
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Parayil Venugopalan, S. (author)
doctoral thesis 2019
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Shamsutdinova, Guzel (author), Hendriks, M.A.N. (author), Jacobsen, Stefan (author)
Topography studies of concrete-ice abrasion were made to proceed in our understanding of the mechanisms of concrete wear by ice on Arctic offshore structures. The effects on various initial surfaces of a B75 normal-weight concrete (smooth, rough, sawn) and on the sawn surface of a LB60 lightweight concrete were studied during concrete-ice...
journal article 2019
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Peeters, J.W.R. (author), Sandham, N. D. (author)
It is well known that rough surfaces affect turbulent flows significantly. How such surfaces affect turbulent heat transfer is less well understood. To gain more insight, we have performed a series of direct numerical simulations of turbulent heat transfer in a channel flow with grit-blasted surfaces. An immersed boundary method is used to...
journal article 2019
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Bruna, P.B.R. (author), Lavenu, Arthur P.C. (author), Matonti, Christophe (author), Bertotti, G. (author)
It sounds counter-intuitive to consider contraction features such as stylolites as potential conduits for flow. However, this idea has grown since 1980, with geoscientists finding many examples principally in carbonate reservoirs where stylolites can be considered as fluid-efficient features. Among others, these features can be reactivated...
journal article 2019
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Jafari, Morez (author), Derlon, Nicolas (author), Desmond, Peter (author), van Loosdrecht, Mark C.M. (author), Morgenroth, Eberhard (author), Picioreanu, C. (author)
Poroelastic fluid-structure interaction models were coupled to experimental data to determine the effects of biofilm spatial distribution of mechanical and hydraulic properties on the biofilm hydraulic resistance and compressibility in membrane filtration processes. Biofilms were cultivated on ultrafiltration membranes for 20 and 30 days...
journal article 2019
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Tummers, M.J. (author), Steunebrink, M. (author)
This paper reports on an experimental study of the effects of surface roughness on the flow and heat transfer in cubical Rayleigh-Bénard convection cells for Rayleigh numbers between 10<sup>7</sup> and 10<sup>10</sup>. In the rough cells the top and bottom surfaces are equipped with square arrays of copper cubes. In line with other studies,...
journal article 2019
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Baron-Hyppolite, C.G. (author), Lashley, C.H. (author), Garzon, Juan (author), Miesse, Tyler (author), Bricker, J.D. (author)
Assessing the accuracy of nearshore numerical models—such as SWAN—is important to ensure their effectiveness in representing physical processes and predicting flood hazards. In particular, for application to coastal wetlands, it is important that the model accurately represents wave attenuation by vegetation. In SWAN, vegetation might be...
journal article 2018
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Abbasi, A. (author), Annor, F.O. (author), van de Giesen, N.C. (author)
A 3-D numerical method is developed to investigate the spatial distribution of surface fluxes over heterogeneous surfaces in (semi-)arid regions. Quantifying the effects of changes in the momentum, thermal and moisture roughness lengths on the airflow and fluxes in the ABL is important for water resources management and local climate studies....
journal article 2018
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van Dokkum, J.S. (author), Khajeh Salehani, M. (author), Irani, N. (author), Nicola, L. (author)
The relative contact area of rough surface contacts is known to increase linearly with reduced pressure, with proportionality factor κ. In its common definition, the reduced pressure contains the root-mean-square gradient (RMSG) of the surface. Although easy to measure, the RMSG of the entire surface does not coincide, at small loads, with...
journal article 2018
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Liu, Y. (author)
A better understanding of the wear mechanism of materials is essential to selecting suitable materials to prolong service time and reduce costs. Wear resistance is not an intrinsic material property but a response to a system including multiples parameters determined by the material, the counter body, the load condition, and the environment....
doctoral thesis 2017
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Ye, Q. (author)
Boundary layer transition is a relevant phenomenon in many aerodynamic and aero-thermodynamic problems and has been extensively investigated from the past century till recent times. Among the factors affecting the transition process, surface roughness plays a key role. When a roughness element with sufficiently large height (<i>h</i>) compared...
doctoral thesis 2017
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Tomas, J.M. (author), Eisma, H.E. (author), Pourquie, M.J.B.M. (author), Elsinga, G.E. (author), Jonker, H.J.J. (author), Westerweel, J. (author)
Both large-eddy simulations (LES) and water-tunnel experiments, using simultaneous stereoscopic particle image velocimetry and laser-induced fluorescence, have been used to investigate pollutant dispersion mechanisms in regions where the surface changes from rural to urban roughness. The urban roughness was characterized by an array of...
journal article 2017
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Faivre, R.D. (author), Colin, Jérôme (author), Menenti, M. (author)
The parameterization of heat transfer based on remote sensing data, and the Surface Energy Balance System (SEBS) scheme to retrieve turbulent heat fluxes, already proved to be very appropriate for estimating evapotranspiration (ET) over homogeneous land surfaces. However, the use of such a method over heterogeneous landscapes (e.g., semi-arid...
journal article 2017
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Yang, L. (author), Padding, J.T. (author), Buist, K. A. (author), Kuipers, J. (author)
Two fluid model simulations based on our recently introduced kinetic theory of granular flow (KTGF) for rough spheres and rough walls, are validated for the first time for full three-dimensional (3D) bubbling fluidized beds. The validation is performed by comparing with experimental data from Magnetic Particle Tracking and more detailed...
journal article 2017
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Basu, S. (author), Lacser, Avraham (author)
In several recent large-eddy simulation studies, the lowest grid level was located well within the roughness sublayer. Monin–Obukhov similarity-based boundary conditions cannot be used under this scenario, and in this note we elaborate on this fundamental problem and suggest potential solutions.
journal article 2017
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Tomas, J.M. (author), Pourquie, M.J.B.M. (author), Jonker, H.J.J. (author)
Large-eddy simulations (LES) are used to investigate the effect of stable stratification on rural-to-urban roughness transitions. Smooth-wall turbulent boundary layers are subjected to a generic urban roughness consisting of cubes in an in-line arrangement. Two line sources of pollutant are added to investigate the effect on pollutant dispersion...
journal article 2016
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Sun, F. (author)
The ultimate objective of this work is to gain a better understanding of the plastic behavior of rough metal surfaces under contact loading. Attention in this thesis focuses on the study of single and multiple asperities with micrometer scale dimensions, a scale at which plasticity is known to be size dependent. The asperities have very simple...
doctoral thesis 2016
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Verduin, T. (author), Lokhorst, S.R. (author), Hagen, C.W. (author), Kruit, P. (author)
In the simulation of secondary electron yields (SEY) and secondary electron microscopy (SEM) images, there is always the question: are we using the correct scattering cross-sections?. The three scattering processes of interest are quasi-elastic phonon scattering, elastic Mott scattering and inelastic scattering using the dielectric function...
journal article 2016
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Ye, Q. (author), Schrijer, F.F.J. (author), Scarano, F. (author)
Boundary layer transition over isolated roughness elements is investigated in the incompressible flow regime using tomographic PIV. Four different geometries (cylinder, square, hemisphere and micro-ramp) are considered maintaining constant height and span of the element. The main target is to compare the different flow topologies and study the...
journal article 2016
Searched for: subject:"roughness"
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