Papers by florian de vuyst
POD-ISAT: An efficient POD-based surrogate approach with adaptive tabulation and fidelity regions for parametrized steady-state PDE discrete solutions
International Journal for Numerical Methods in Engineering, Feb 1, 2013
ABSTRACT SUMMARYA combination of proper orthogonal decomposition (POD) analysis and in situ adapt... more ABSTRACT SUMMARYA combination of proper orthogonal decomposition (POD) analysis and in situ adaptive tabulation (ISAT) is proposed for the representation of parameter-dependent solutions of coupled partial differential equation problems. POD is used for the low-order representation of the spatial fields and ISAT for the local representation of the solution in the design parameter space. The accuracy of the method is easily controlled by free threshold parameters that can be adjusted according to user needs. The method is tested on a coupled fluid-thermal problem: the design of a simplified aircraft air control system. It is successfully compared with the standard POD; although the POD is inaccurate in certain areas of the design parameters space, the POD–ISAT method achieves accuracy thanks to trust regions based on residuals of the fluid-thermal problem. The presented POD–ISAT approach provides flexibility, robustness and tunable accuracy to represent solutions of parametrized partial differential equations.Copyright © 2013 John Wiley & Sons, Ltd.
arXiv (Cornell University), Mar 1, 2017
The Lagrange-Flux schemes are Eulerian finite volume schemes that make use of an approximate Riem... more The Lagrange-Flux schemes are Eulerian finite volume schemes that make use of an approximate Riemann solver in Lagrangian description with particular upwind convective fluxes. They have been recently designed as variant formulations of Lagrange-remap schemes that provide better HPC performance on modern multicore processors, see [De Vuyst et al., OGST 71(6), 2016]. Actually Lagrange-Flux schemes show several advantages compared to Lagrange-remap schemes, especially for multidimensional problems: they do not require the computation of deformed Lagrangian cells or mesh intersections as in the remapping process. The paper focuses on the entropy property of Lagrange-Flux schemes in their semi-discrete in space form, for one-dimensional problems and for the compressible Euler equations as example. We provide pseudo-viscosity pressure terms that ensure entropy production of order O(|∆ u| 3), where |∆ u| represents a velocity jump at a cell interface. Pseudo-viscosity terms are also designed to vanish into expansion regions as it is the case for rarefaction waves.
International Journal for Multiscale Computational Engineering, 2018
This paper focuses on solving coupled problems of lumped parameter models. Such problems are of i... more This paper focuses on solving coupled problems of lumped parameter models. Such problems are of interest for the simulation of severe accidents in nuclear reactors : these coarse-grained models allow for fast calculations for statistical analysis used for risk assessment and solutions of large problems when considering the whole severe accident scenario. However, this modeling approach has several numerical flaws. Besides, in this industrial context, computational efficiency is of great importance leading to various numerical constraints. The objective of this research is to analyze the applicability of explicit coupling strategies to solve such coupled problems and to design implicit coupling schemes allowing stable and accurate computations. The proposed schemes are theoretically analyzed and tested within CEA's PROCOR platform on a problem of heat conduction solved with coupled lumped parameter models and coupled 1D models. Numerical results are discussed and allow us to emphasize the benefits of using the designed coupling schemes instead of the usual explicit coupling schemes.
Efficient Time-Dependent PDE Computation using MATLAB and SCILAB
Reduced-order modelling of randomly parameterized PDEs
Progress in Multiphase Flow Research, 2007
Empirical Interpolation Decomposition
HAL (Le Centre pour la Communication Scientifique Directe), Nov 12, 2018
Many physical problems need a multidimensional description and involve high dimensional spaces. S... more Many physical problems need a multidimensional description and involve high dimensional spaces. Standard discretization techniques often lead to an excessive computation time. To solve this problem, we develop in this paper an empirical interpolation decomposition (EID) for multivariate functions. This method provides an approximate representation of a given function in separate form. Error estimates of the developed EID are derived and some properties are given.
Demo: free boundary flow computation. Numerical simulation of the horizontal sloshing of a tank filled with water at 85%
free boundary flow computation. Numerical simulation of the horizontal sloshing of a tank filled ... more free boundary flow computation. Numerical simulation of the horizontal sloshing of a tank filled with water at 85%.
Performance modeling of a compressible hydrodynamics solver on multicore CPUs
Parallel Computing, 2015
arXiv (Cornell University), Jun 13, 2023
A data-driven reduced order model for partitioned fluid-structure interactions • A new approach, ... more A data-driven reduced order model for partitioned fluid-structure interactions • A new approach, coupling a reduced order solid model, and a full order fluid model • Reduction of elastic quasi-static solid models coupled with less expensive fluid models • Linear and nonlinear dimensionality reduction for forces and displacement fields • Parsimonious regression models to learn the solid model in the latent space
Empirical Interpolation Decomposition
Acta Applicandae Mathematicae, Nov 12, 2018
Many physical problems need a multidimensional description and involve high dimensional spaces. S... more Many physical problems need a multidimensional description and involve high dimensional spaces. Standard discretization techniques often lead to an excessive computation time. To solve this problem, we develop in this paper an empirical interpolation decomposition (EID) for multivariate functions. This method provides an approximate representation of a given function in separate form. Error estimates of the developed EID are derived and some properties are given.
HAL (Le Centre pour la Communication Scientifique Directe), 2006
Cet article présente la démarche multidisciplinaire que nous avons adoptée pour construire un sys... more Cet article présente la démarche multidisciplinaire que nous avons adoptée pour construire un système d'information pour l'aideà la décision dans la gestion du trafic routier. L'architecture du système, le schéma de l'entrepôt de données ainsi que les différentes représentations numériques et symboliques des séquences spatio-temporelles, stockées dans l'entrepôt, y sont détaillés.
A geometrically accurate low-diffusive conservative interface capturing method suitable for multimaterial flows
Computers & Fluids, Sep 1, 2021
Abstract This paper is dedicated to the design of an artifact-free and geometrically accurate low... more Abstract This paper is dedicated to the design of an artifact-free and geometrically accurate low-diffusive interface capturing method for pure advection problems with extension to the multifluid/multimaterial case. The numerical method involves a genuinely multidimensional gradient limiting process that provides interface reconstruction accuracy without appearance of usually-encountered artifacts like zigzag-shaped instabilities or broken line-type attractors especially when Cartesian meshes are used. The approach is also extended to the multimaterial cases that gives very promising results. In particular, the well-known stretching Kothe-Rider test case has been extended up to five materials and provide convincing results.
Numerical solution of the Vlasov–Poisson system using generalized Hermite functions
Computer Physics Communications, Oct 1, 2006
ABSTRACT Two different spectral approaches for solving the nonlinear Vlasov–Poisson equations are... more ABSTRACT Two different spectral approaches for solving the nonlinear Vlasov–Poisson equations are presented and discussed. The first approach is based on a standard spectral Galerkin method (SGM) using Hermite functions in the velocity space. The second method which belongs to the family of pseudospectral methods (SCM) uses Gauss–Hermite collocation points for the velocity discretization. The high-dimensional feature of these equations and the suspected presence of small scales in the solution suggested us to employ these methods that provide high order accuracy while considering a “small” number of ad hoc basis functions. The scaled Hermite functions allow us to treat the case of unbounded domains and to properly recover Gaussian-type distributions. Some numerical results on usual test cases are shown and prove the good agreement with the theory.
HAL (Le Centre pour la Communication Scientifique Directe), Feb 18, 2022
In a recent paper [Poncet R., Peybernes M., Gasc T., De Vuyst F. (2016) Performance modeling of a... more In a recent paper [Poncet R., Peybernes M., Gasc T., De Vuyst F. (2016) Performance modeling of a compressible hydrodynamics solver on multicore CPUs, in "Parallel Computing: on the road to Exascale"], we have achieved the performance analysis of staggered Lagrange-remap schemes, a class of solvers widely used for hydrodynamics applications. This paper is devoted to the rethinking and redesign of the Lagrange-remap process for achieving better performance using today's computing architectures. As an unintended outcome, the analysis has lead us to the discovery of a new family of solversthe so-called Lagrange-flux schemesthat appear to be promising for the CFD community. Résumé-Schémas Lagrange-flux : reformuler les schémas Lagrange-Projection d'ordre deux pour améliorer la performance HPC au niveau noeud de calcul-Dans un article récent [Poncet R., Peybernes M., Gasc T., De Vuyst F. (2016) Performance modeling of a compressible hydrodynamics solver on multicore CPUs, in "Parallel Computing: on the road to Exascale"], nous avons effectué l'analyse de la performance d'un schéma de type Lagrange+projection à variables décalées ; cette classe de solveurs est très utilisée pour les applications d'hydrodynamique. Dans cet article, on s'intéresse à la reformulation des solveurs Lagrange-projection afin d'améliorer leur performance globale sur architectures de calculs standards. De manière inattendue, l'analyse nous a conduit vers la découverte d'une nouvelle famille de solveursappelés schémas Lagrange-fluxqui apparaissent comme très prometteurs dans la communauté CFD.
HAL (Le Centre pour la Communication Scientifique Directe), Jun 21, 2013
arXiv (Cornell University), 2022
In this paper, we present a generic approach of a dynamical data-driven model order reduction tec... more In this paper, we present a generic approach of a dynamical data-driven model order reduction technique for three-dimensional fluid-structure interaction problems. A low-order continuous linear differential system is identified from snapshot solutions of a high-fidelity solver. The reduced order model (ROM) uses different ingredients like proper orthogonal decomposition (POD), dynamic mode decomposition (DMD) and Tikhonov-based robust identification techniques. An interpolation method is used to predict the capsule dynamics for any value of the governing non-dimensional parameters that are not in the training database. Then a dynamical system is built from the predicted solution. Numerical evidence shows the ability of the reduced model to predict the time-evolution of the capsule deformation from its initial state, whatever the parameter values. Accuracy and stability properties of the resulting low-order dynamical system are analyzed numerically. The numerical experiments show a very good agreement, measured in terms of modified Hausdorff distance between capsule solutions of the full-order and low-order models both in the case of confined and unconfined flows. This work is a first milestone to move towards real time simulation of fluid-structure problems, which can be extended to non-linear low-order systems to account for strong material and flow non-linearities. It is a valuable innovation tool for rapid design and for the development of innovative devices.
HAL (Le Centre pour la Communication Scientifique Directe), Feb 18, 2022
This research is aimed at achieving an efficient digital infrastructure for evaluating risks and ... more This research is aimed at achieving an efficient digital infrastructure for evaluating risks and damages caused by tsunami flooding. This research has been mainly focused on the suitable modeling of debris dynamics for a simple (but accurate enough) assessment of damages. For different reasons including computational performance and Big Data management issues, we focus our research on Eulerian debris flow modeling. Rather than using complex multiphase debris models, we rather use an empirical transportation and deposition model that takes into account the interaction with the main water flow, friction/contact with the ground but also debris interaction. In particular, for debris interaction, we have used ideas coming from vehicular traffic flow modeling. We introduce a velocity regularization term similar to the so-called "anticipation term" in traffic flow modeling that takes into account the local flow between neighboring debris and makes the problem mathematically well-posed. It prevents from the generation of "Dirac measures of debris" at shock waves. As a result, the model is able to capture emerging phenomenons like debris aggregation and accumulations, and possibly to react on the main flow by creating hills of debris and make the main stream deviate. We also discuss the way to derive quantities of interest (QoI), especially "damage functions" from the debris density and momentum fields. We believe that this original unexplored debris approach can lead to a valuable analysis of tsunami flooding damage assessment with Physics-based damage functions. Numerical experiments show the nice behaviour of the numerical solvers, including the solution of Saint-Venant's shallow water equations and debris dynamics equations.
AGU Fall Meeting Abstracts, Dec 1, 2017
This article has been accepted for publication and undergone full peer review but has not been th... more This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as
Assessment of SPH method variants for sloshing problems: comparison to experimental results
HAL (Le Centre pour la Communication Scientifique Directe), 2013
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Papers by florian de vuyst