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Numerical modelling of finite-size particle collisions in a viscous fluid

Brändle de Motta, J.C. (author), Breugem, W.P. (author), Gazanion, B. (author), Estivalezes, J.L. (author), Vincent, S. (author), Climent, E. (author)

A general model is presented for short-range hydrodynamic interactions and head-on particle-particle/wall collisions. The model has been embedded in two distinct numerical methods for fully resolved simulation of finite-size particles in a viscous fluid. It accounts for the material properties of the particles and lubrication effects prior to...

journal article 2013

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On the levitation force in horizontal core-annular flow with a large viscosity ratio and small density ratio

Ooms, G. (author), Pourquie, M.J.B.M. (author), Beerens, J.C. (author)

A numerical study has been made of horizontal core-annular flow: the flow of a high-viscosity liquid core surrounded by a low-viscosity liquid annular layer through a horizontal pipe. Special attention is paid to the question how the buoyancy force on the core, caused by a density difference between the core and the annular layer, is...

journal article 2013

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Large-eddy simulation of highly underexpanded transient gas jets

Vuorinen, V. (author), Yu, J. (author), Tirunagari, S. (author), Kaario, O. (author), Larmi, M. (author), Duwig, C. (author), Boersma, B.J. (author)

Large-eddy simulations (LES) based on scale-selective implicit filtering are carried out in order to study the effect of nozzle pressure ratios on the characteristics of highly underexpanded jets. Pressure ratios ranging from 4.5 to 8.5 with Reynolds numbers of the order 75?000–140?000 are considered. The studied configuration agrees well with...

journal article 2013

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Energy spectra and turbulence generation in the wake of magnetic obstacles

Kenjeres, S. (author)

Numerical simulations and analysis of flow and heat transfer of an electrically conducting fluid past magnetic obstacles are reported. We studied the channel flow configuration with electrically and thermally insulated horizontal walls containing a single or multiple (two or three) magnetic dipoles. Different values of the interactive parameter...

journal article 2012

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Modeling of low-capillary number segmented flows in microchannels using OpenFOAM

Hoang, D.A. (author), Van Steijn, V. (author), Portela, L.M. (author), Kreutzer, M.T. (author), Kleijn, C.R. (author)

Modeling of low-Capillary number segmented flows in microchannels is important for the design of microfluidic devices. We present numerical validations of microfluidic flow simulations using the volume-of-fluid (VOF) method as implemented in OpenFOAM. Two benchmark cases were investigated to ensure the reliability of OpenFOAM in modeling complex...

conference paper 2012

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Electromagnetically driven dwarf tornados in turbulent convection

Kenjeres, S. (author)

Motivated by the concept of interdependency of turbulent flow and electromagnetic fields inside the spiraling galaxies, we explored the possibilities of generating a localized Lorentz force that will produce a three-dimensional swirling flow in weakly conductive fluids. Multiple vortical flow patterns were generated by combining arrays of...

journal article 2011

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Resistances for heat and mass transfer through a liquid–vapor interface in a binary mixture

Glavatskiy, K.S. (author), Bedeaux, D. (author)

In this paper we calculate the interfacial resistances to heat and mass transfer through a liquid–vapor interface in a binary mixture. We use two methods, the direct calculation from the actual nonequilibrium solution and integral relations, derived earlier. We verify, that integral relations, being a relatively faster and cheaper method, indeed...

journal article 2010

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Turbulence modulation and drag reduction by spherical particles

Zhao, L.H. (author), Andersson, H.I. (author), Gillissen, J.J.J. (author)

This letter reports on the pronounced turbulence modulations and the accompanying drag reduction observed in a two-way coupled simulation of particle-laden channel flow. The present results support the view that drag reduction can be achieved not only by means of polymeric or fiber additives but also with spherical particles.

journal article 2010

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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

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Influence of rarefaction on the flow dynamics of a stationary supersonic hot-gas expansion

Abbate, G. (author), Kleijn, C.R. (author), Thijsse, B.J. (author), Engeln, R. (author), Van de Sanden, M.C.M. (author), Schram, D.C. (author)

The gas dynamics of a stationary hot-gas jet supersonically expanding into a low pressure environment is studied through numerical simulations. A hybrid coupled continuum-molecular approach is used to model the flow field. Due to the low pressure and high thermodynamic gradients, continuum mechanics results are doubtful, while, because of its...

journal article 2008

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The stress generated by non-Brownian fibers in turbulent channel flow simulations

Gillissen, J.J.J. (author), Boersma, B.J. (author), Mortensen, P.H. (author), Andersson, H.I. (author)

Turbulent fiber suspension channel flow is studied using direct numerical simulation. The effect of the fibers on the fluid mechanics is governed by a stress tensor, involving the distribution of fiber position and orientation. Properties of this function in channel flow are studied by computing the trajectories and orientations of individual...

journal article 2007

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On the performance of the moment approximation for the numerical computation of fiber stress in turbulent channel flow

Gillissen, J.J.J. (author), Boersma, B.J. (author), Mortensen, P.H. (author), Andersson, H.I. (author)

Fiber-induced drag reduction can be studied in great detail by means of direct numerical simulation [ J. S. Paschkewitz et al., J. Fluid Mech. 518, 281 (2004) ]. To account for the effect of the fibers, the Navier-Stokes equations are supplemented by the fiber stress tensor, which depends on the distribution function of fiber orientation angles....

journal article 2007

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Subcritical flow past a circular cylinder surrounded by a porous layer

Sobera, M.P. (author), Kleijn, C.R. (author), Van den Akker, H.E.A. (author)

A study of the flow at subcritical Re = 3900 around a circular cylinder, surrounded at some fixed small distance by a porous layer with a hydraulic resistance typical for that of textile materials, has been performed by means of direct numerical simulations. The flow in the space between the porous layer and the solid cylinder was found to be...

journal article 2006

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On the spatial linear growth of gravity-capillary water waves sheared by a laminar air flow

Tsai, Y.S. (author), Grass, A.J. (author), Simons, R.R. (author)

The initial growth of mechanically generated small amplitude water waves below a laminar air stream was examined numerically and experimentally in order to explore the primary growth mechanism, that is, the interfacial instability of coupled laminar air and water flows. Measurements of the laminar velocity profile in the air over the water...

journal article 2005

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Identification of the wind in Rayleigh–Bénard convection

Van Reeuwijk, M. (author), Jonker, H.J.J. (author), Hanjali?, K. (author)

Using a symmetry-accounting ensemble-averaging method, we have identified the wind in unbounded Rayleigh–Bénard convection. This makes it possible to distinguish the wind from fluctuations and to identify dynamic features of each. We present some results from processing five independent three-dimensional direct numerical simulations of a ? = 4...

journal article 2005

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Turbulence characteristics in sharp open-channel bends

Blanckaert, K. (author), De Vriend, H.J. (author)

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...

journal article 2005

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Capture and inception of bubbles near line vortices

Oweis, G.F. (author), Van der Hout, I.E. (author), Tryggvason, G. (author), Ceccio, S.L. (author)

Motivated by the need to predict vortex cavitation inception, a study has been conducted to investigate bubble capture by a concentrated line vortex of core size rc and circulation ?0 under noncavitating and cavitating conditions. Direct numerical simulations that solve simultaneously for the two phase flow field, as well as a simpler one-way...

journal article 2005

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Direct numerical simulations of turbulent flow over a permeable wall using a direct and a continuum approach

Breugem, W.P. (author), Boersma, B.J. (author)

A direct numerical simulation (DNS) has been performed of turbulent channel flow over a three-dimensional Cartesian grid of 30×20×9 cubes in, respectively, the streamwise, spanwise, and wall-normal direction. The grid of cubes mimics a permeable wall with a porosity of 0.875. The flow field is resolved with 600×400×400 mesh points. To enforce...

journal article 2005

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Energy transfers and spectral eddy viscosity in large-eddy simulations of homogeneous isotropic turbulence: Comparison of dynamic Smagorinsky and multiscale models over a range of discretizations

Hughes, T.J.R. (author), Wells, G.N. (author), Wray, A.A. (author)

Energy transfers within large-eddy simulation (LES) and direct numerical simulation (DNS) grids are studied. The spectral eddy viscosity for conventional dynamic Smagorinsky and variational multiscale LES methods are compared with DNS results. Both models underestimate the DNS results for a very coarse LES, but the dynamic Smagorinsky model is...

journal article 2004

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Sensitivity of the scale partition for variational multiscale large-eddy simulation of channel flow

Holmen, J. (author), Hughes, T.J.R. (author), Oberai, A.A. (author), Wells, G.N. (author)

The variational multiscale method has been shown to perform well for large-eddy simulation (LES) of turbulent flows. The method relies upon a partition of the resolved velocity field into large- and small-scale components. The subgrid model then acts only on the small scales of motion, unlike conventional LES models which act on all scales of...

journal article 2004