Searched for: subject:"Subgrid"
(1 - 15 of 15)
document
Dai, Y. (author)
In current study, several fundamental and inherent problems in original Deardorff subgrid model are identified under stably stratified condition. It is found that the mixing length parameterization in this subgrid model is at the root of a long trouble problem of grid size sensitivity in large-eddy simulation (LES). A new formulation of mixing...
master thesis 2020
document
Couvreux, Fleur (author), Bazile, Eric (author), Rodier, Quentin (author), Maronga, Björn (author), Matheou, Georgios (author), Chinita, Maria J. (author), Edwards, John (author), van Stratum, Bart J.H. (author), van Heerwaarden, Chiel C. (author), Huang, Jing (author), Moene, Arnold F. (author), Cheng, Anning (author), Fuka, Vladimir (author), Basu, S. (author), Bou-Zeid, Elie (author), Canut, Guylaine (author), Vignon, Etienne (author)
In polar regions, where the boundary layer is often stably stratified, atmospheric models produce large biases depending on the boundary-layer parametrizations and the parametrization of the exchange of energy at the surface. This model intercomparison focuses on the very stable stratification encountered over the Antarctic Plateau in 2009. Here...
journal article 2020
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Dai, Y. (author), Basu, S. (author), Maronga, Björn (author), de Roode, S.R. (author)
We have identified certain fundamental limitations of a mixing-length parametrization used in a popular turbulent kinetic energy-based subgrid-scale model. Replacing this parametrization with a more physically realistic one significantly improves the overall quality of the large-eddy simulation (LES) of stable boundary layers. For the range...
journal article 2020
document
Robijns, Michel (author)
This thesis is part of a greater effort to use machine learning for the development of flexible and universal unresolved-scale models in large eddy simulation (LES). The novelty in the current work is that a neural network learns to predict the integral forms of the unresolved-scale terms directly without a priori assumptions on the underlying...
master thesis 2019
document
Gnanasundaram, Arun (author)
The whole construct of explicit algebraic Reynolds stress models, as they are known in RANS, is based on the weak equilibrium assumption. By employing this assumption, and in addition, incorporating models for terms in the Reynolds stress transport equations, the system of six partial differential equations can be simplified to an algebraic form...
master thesis 2018
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Platzek, F.W. (author)
A river engineer is challenged with the task of setting up an appropriate model for a certain application. The model needs to provide suitable answers to the questions asked (i.e. be effective) and needs to do this within the available time (i.e. be efficient). To set up such a model with sufficient accuracy and certainty, a modeller needs to...
doctoral thesis 2017
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Rijnsdorp, D.P. (author), Smit, Pieter B. (author), Zijlema, M. (author), Reniers, A.J.H.M. (author)
Wave-induced currents are an ubiquitous feature in coastal waters that can spread material over the surf zone and the inner shelf. These currents are typically under resolved in non-hydrostatic wave-flow models due to computational constraints. Specifically, the low vertical resolutions adequate to describe the wave dynamics – and required to...
journal article 2017
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Dorrestijn, J. (author), Crommelin, D.T. (author), Siebesma, A.P. (author), Jonker, H.J.J. (author), Selten, F. (author)
Conditional Markov chain (CMC) models have proven to be promising building blocks for stochastic convection parameterizations. In this paper, it is demonstrated how two different CMC models can be used as mass flux closures in convection parameterizations. More specifically, the CMC models provide a stochastic estimate of the convective area...
journal article 2016
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Volp, N.D. (author), van Prooijen, B.C. (author), Pietrzak, J.D. (author), Stelling, G.S. (author)
Long term morphodynamic simulations are used for predicting the impact of climate change and human interventions in our estuarine and coastal regions. The accuracy of this type of simulations suffers generally from low resolution grids. Eventhough high resolution bathymetry data is increasingly more available thanks to new measurement techniques...
abstract 2016
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Maher, G.D. (author), Hulshoff, S.J. (author)
The Variational Germano Identity [1, 2] is used to optimize the coefficients of residual-based subgrid-scale models that arise from the application of a Variational Multiscale Method [3, 4]. It is demonstrated that numerical iterative methods can be used to solve the Germano relations to obtain values for the parameters of subgrid-scale models...
conference paper 2014
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Volp, N.D. (author), Van Prooijen, B.C. (author), Stelling, G.S. (author)
This study presents a finite volume hydrodynamic model for shallow water flow that computes on a coarse grid, but accounts for high-resolution bathymetry and roughness variations on a subgrid. The detailed information can be incorporated by using the assumption of a uniform flow direction and a uniform friction slope within a part of a coarse...
journal article 2013
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Winckelmans, G. (author), Cocle, R. (author), Dufresne, L. (author), Capart, R. (author), Bricteux, L. (author), Daeninck, G. (author), Lonfils, T. (author), Duponcheel, M. (author), Desenfans, O. (author), Georges, L. (author)
This paper aims at presenting DNS and LES as applied to the simulation of vortex wakes: in laboratory conditions (moderate to medium Reynolds numbers) and up to real aircraft conditions (high to very high Reynolds numbers). Only incompressible flows are considered. DNS and LES are able to capture complex 3-D physics provided one uses high...
conference paper 2006
document
Paul, S.C. (author), Paul, M.C. (author), Jones, W.P. (author)
In this work we investigate turbulent non-premixed combustion, including species concentrations and temperature, in a model of 3D cylindrical combustor. Gaseous propane (C3H8) and preheated air with temperature of 773K are injected through the combustor inlet. A Large Eddy Simulation (LES) technique is applied to solve the governing equations of...
conference paper 2006
document
Lube, G. (author)
The numerical solution of the nonstationary, incompressible Navier-Stokes model can be split into linearized auxiliary problems of Oseen type. We present in a unique way different stabilization techniques of finite element schemes on isotropic and hybrid meshes. First we describe the state-of-the-art for the classical residual-based SUPG/PSPG...
conference paper 2006
document
Dorrestijn, J. (author), Crommelin, D.T. (author), Siebesma, A.P. (author), Jonker, H.J.J. (author), Jakob, C. (author)
Observational data of rainfall from a rain radar in Darwin, Australia, are combined with data defining the large-scale dynamic and thermodynamic state of the atmosphere around Darwin to develop a multicloud model based on a stochastic method using conditional Markov chains. The authors assign the radar data to clear sky, moderate congestus,...
journal article
Searched for: subject:"Subgrid"
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