Searched for: subject%3A%22variational%255C+multiscale%255C+method%22
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Shrestha, Suyash (author)
Structure-preserving or mimetic discretisations are a class of advanced discretisation techniques derived by employing concepts from differential geometry. Such techniques can attain specific conservation properties at the discrete level such as conservation of mass, kinetic energy, etc when applied to conservation laws. However, like...
master thesis 2022
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Janssens, M. (author), Hulshoff, S.J. (author)
Data-driven parameterizations offer considerable potential for improving the fidelity of General Circulation Models. However, ensuring that these remain consistent with the governing equations while still producing stable simulations remains a challenge. In this paper, we propose a combined Variational-Multiscale (VMS) Artificial Neural...
journal article 2022
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Chen, Linfeng (author), Hulshoff, S.J. (author), Dong, Yuhong (author)
The underlying physical mechanism of the residual-based large eddy simulation (LES) based on the variational multiscale (VMS) method is clarified. Resolved large-scale energy transportation equation is mathematically derived for turbulent kinetic energy budget analysis. Firstly, statistical results of benchmark turbulent channel flow at Re...
journal article 2022
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Rajampeta, Sharath (author)
The use of Large Eddy Simulations(LES) in industry is steadily increasing as the complexity of the problems are increasing. However there remains a potential for significant improvements in LES. The Variational Multiscale Method(VMM) introduced by Hughes et al. (1998) provides a more consistent framework for turbulence modelling. The use of an...
master thesis 2021
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Stoter, Stein K.F. (author), ten Eikelder, M.F.P. (author), de Prenter, Frits (author), Akkerman, I. (author), van Brummelen, E. Harald (author), Verhoosel, Clemens V. (author), Schillinger, Dominik (author)
We show that in the variational multiscale framework, the weak enforcement of essential boundary conditions via Nitsche's method corresponds directly to a particular choice of projection operator. The consistency, symmetry and penalty terms of Nitsche's method all originate from the fine-scale closure dictated by the corresponding scale...
journal article 2021
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Pusuluri, Abhinand (author)
An effective way to solve the forced Burgers' equation in a variational multiscale framework is to close the system of equations using unresolved-scale interaction terms predicted by an artificial neural network. The goal of this thesis is to investigate the accuracy and stability of the said system by training a neural network offline with data...
master thesis 2020
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ten Eikelder, M.F.P. (author), Bazilevs, Y. (author), Akkerman, I. (author)
In this paper we show that the variational multiscale method together with the variation entropy concept form the underlying theoretical framework of discontinuity capturing. The variation entropy [M.F.P. ten Eikelder and I. Akkerman, Comput. Methods Appl. Mech. Engrg. 355 (2019) 261-283] is the recently introduced concept that equips total...
journal article 2020
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Shen, Zhongwei (author)
This master thesis presents the computation of free-surface flow phenomena with emphasis on ship hydromechanics. We perform a simulation of the heave and the pitch motion of the DTMB 5415M ship moving in head sea. To this purpose we employ an existing Arbitrary-Lagrangian-Eulerian residual-based variational multiscale method (ALE-RBVMS) to...
master thesis 2019
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Janssens, Martin (author)
Today's leading projections of climate change predicate on Atmospheric General Circulation Models (GCMs). Since the atmosphere consists of a staggering range of scales that impact global trends, but computational constraints prevent many of these scales from being directly represented in numerical simulations, GCMs require "parameterisations'' -...
master thesis 2019
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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
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Stoter, Stein K.F. (author), Turteltaub, S.R. (author), Hulshoff, S.J. (author), Schillinger, Dominik (author)
We initiate the study of the discontinuous Galerkin residual-based variational multiscale (DG-RVMS) method for incorporating subgrid-scale behavior into the finite element solution of hyperbolic problems. We use the one-dimensional viscous Burgers equation as a model problem, as its energy dissipation mechanism is analogous to that of turbulent...
journal article 2018
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ten Eikelder, M.F.P. (author), Akkerman, I. (author)
This paper presents the construction of novel stabilized finite element methods in the convective–diffusive context that exhibit correct-energy behavior. Classical stabilized formulations can create unwanted artificial energy. Our contribution corrects this undesired property by employing the concepts of dynamic as well as orthogonal small...
journal article 2018
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Stoter, Stein K.F. (author), Turteltaub, S.R. (author), Hulshoff, S.J. (author), Schillinger, Dominik (author)
We develop the general form of the variational multiscale method in a discontinuous Galerkin framework. Our method is based on the decomposition of the true solution into discontinuous coarse-scale and discontinuous fine-scale parts. The obtained coarse-scale weak formulation includes two types of fine-scale contributions. The first type...
journal article 2018
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ten Eikelder, M.F.P. (author), Akkerman, I. (author)
This paper presents the construction of a correct-energy stabilized finite element method for the incompressible Navier–Stokes equations. The framework of the methodology and the correct-energy concept have been developed in the convective–diffusive context in the preceding paper [M.F.P. ten Eikelder, I. Akkerman, Correct energy evolution of...
journal article 2018
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Navarro Hernandez, L.C. (author)
The Large Eddy Simulation of high Reynolds number wall-bounded flows, has grid refinement requirements in near-wall regions similar to those of DNS. The feasibility of such computations is restricted by their elevated costs and therefore alternate solutions must be employed. While several methods to couple LES and RANS have been proposed, most...
master thesis 2015
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Chen, L. (author), Maher, G.D. (author), Hulshoff, S.J. (author)
Parameters for SGS models within the variational multiscale method for the Stokes equations are determined using two different methods. Both linear and nonlinear models are considered. Firstly, optimal parameters are found using a goal-oriented model-constrained technique minimising L2 error. Secondly, parameters are obtained using the...
conference paper 2014
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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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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
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John, V. (author), Tambulea, A. (author)
Two realizations of finite element variational multiscale (VMS) methods for the simulation of incompressible turbulent flows are studied. The difference between the two approaches consists in the way the spaces for the large scales and the resolved small scales are chosen. The paper addresses issues of the implementation of these methods, the...
conference paper 2006
document
Munts, E.A. (author)
The Variational Multiscale (VMS) method has appeared as a promising new approach to the Large Eddy Simulation (LES) of turbulent flows. The key advantage of the VMS approach is that it allows different subgrid-scale (SGS) modeling assumptions to be made at different ranges of the resolved scales. Typically, in the VMS method, SGS modeling is...
doctoral thesis 2006
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