Cerfacs Entrez dans le monde de la haute performance...

Le Cerfacs en bref

Centre de recherche fondamentale et appliquée spécialisé dans la modélisation et la simulation numériques, également centre de formation avancée, le Cerfacs, par ses moyens et son savoir-faire en calcul haute performance, traite des grands problèmes scientifiques et techniques de recherche publique et industrielle sur les secteurs suivants: AERONAUTIQUE&AUTOMOBILEESPACEENERGIEENVIRONNEMENT&CLIMAT
Ses effectifs sont de l'ordre de 100-150 chercheurs, ingénieurs et administratifs.

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LES ACTUALITÉS

La simulation en combustion, un des thèmes discutés à l'Académie le 9 mai pour le colloque « Les simulations « frontières » en mécanique des solides et des fluides »

28 mars 2017

La simulation en combustion, un des thèmes discutés à l'Académie le 9 mai pour le colloque « Les simulations « frontières » en mécanique des solides et des fluides »

Le 9 mai après midi, l’Académie organise un colloque sur le thème "Les simulations « frontières » en mécanique des solides et des fluides » T. Poinsot présentera les travaux les plus récents dans le domaine de la combustion numérique, obtenus en collaboration par le CERFACS avec les laboratoires CNRS et l’ONERA (programme ici). Au même colloque, F. Nicoud (ancien chercheur senior et aujourd’hui consultant CERFACS) décrira les travaux de simulation en hémodynamique.Lire la suite


Le CERFACS partenaire de la Chaire ANR industrielle POSEIDON, inaugurée le 27 Janvier à l'Ecole Polytechnique

14 mars 2017

POSEIDON, une des 5 chaires ANR industrielles sélectionnées en 2016, s'intéresse aux « Nouveaux propulseurs plasmas pour satellites en orbite basse terrestre ». Porté par Anne Bourdon du Laboratoire de Physique des Plasmas, ce projet rassemble l’Ecole Polytechnique, le CNRS et Safran Aircraft Engines en vue de développer une nouvelle méthodologie expérimentale et numérique permettant de réduire le nombre de tests expérimentaux pour le développement des futurs propulseurs à effet Hall. Le CERFACS apporte son expertise pour la simulation 3D en géométrie réelle de ces propulseurs. Crédit Ph. Auvray, LPPLire la suite

Toute l'actualité

NOS PUBLICATIONS

Tommasi, D., Stock, C. A., Hobday, A. J., Methot, R., Kaplan, I. C., Eveson, J. P., Holsman, K., Miller, T. J., Gaichas, S., Gehlen, M., Pershing, A., Vecchi, G. A., Msadek, R., Delworth, T., Eakin, C. M., Haltuch, M. A., Séférian, R., Spillman, C. M., Hartog, J. R., Siedlecki, S., Samhouri, J. F., Muhling, B., Asch, R., Pinsky, M. L., Saba, V. S., Kapnick, S. B., Gaitan, C. F., Rykaczewski, R. R., Alexander, M. A., Xue, Y., Pegion, K. V., Lynch, P., Payne, M. R., Kristiansen, T., Lehodey, P. and Werner, F. E. (2017) Managing living marine resources in a dynamic environment : The role of seasonal to decadal climate forecasts, Progress in Oceanography (152), pp. 15-49, doi:/10.1016/j.pocean.2016.12.011

[pdf] [doi]

@ARTICLE{AR-CMGC-17-45, author = {Tommasi, D. and Stock, C.A. and Hobday, A.J. and Methot, R. and Kaplan, I.C. and Eveson, J.P. and Holsman, K. and Miller, T.J. and Gaichas, S. and Gehlen, M. and Pershing, A. and Vecchi, G.A. and Msadek, R. and Delworth, T. and Eakin, C.M. and Haltuch, M.A. and Séférian, R. and Spillman, C.M. and Hartog, J.R. and Siedlecki, S. and Samhouri, J.F. and Muhling , B. and Asch, RG. and Pinsky, M.L. and Saba, V.S. and Kapnick, S.B. and Gaitan, C.F. and Rykaczewski, R.R. and Alexander, M.A. and Xue, Y. and Pegion, K.V. and Lynch, P. and Payne, M.R. and Kristiansen, T. and Lehodey, P. and Werner, F.E. }, title = {Managing living marine resources in a dynamic environment : The role of seasonal to decadal climate forecasts}, year = {2017}, number = {152}, pages = {15-49}, doi = {/10.1016/j.pocean.2016.12.011}, journal = {Progress in Oceanography}, pdf = {http://cerfacs.fr/wp-content/uploads/2017/03/GlobC-Article-Msadek-Mars2017.pdf}}

Vanharen, J., Puigt, G., Vasseur, X., Boussuge, J. -F. and Sagaut, P. (2016) Revisiting the spectral analysis for high-order spectral discontinuous methods, Journal of Computational Physics, 337, pp. 379–402, doi:10.1016/j.jcp.2017.02.043

[url] [doi]

@ARTICLE{AR-CFD-16-120, author = {Vanharen, J. and Puigt, G. and Vasseur, X. and Boussuge, J.-F. and Sagaut, P. }, title = {Revisiting the spectral analysis for high-order spectral discontinuous methods}, year = {2016}, volume = {337}, pages = {379–402}, doi = {10.1016/j.jcp.2017.02.043}, journal = {Journal of Computational Physics}, abstract = {The spectral analysis is a basic tool to characterise the behaviour of any convection scheme. By nature, the solution projected onto the Fourier basis enables to estimate the dissipation and the dispersion associated with the spatial discretisation of the hyperbolic linear problem. In this paper, we wish to revisit such analysis, focusing attention on two key points. The first point concerns the effects of time integration on the spectral analysis. It is shown with standard high-order Finite Difference schemes dedicated to aeroacoustics that the time integration has an effect on the required number of points per wavelength. The situation depends on the choice of the coupled schemes (one for time integration, one for space derivative and one for the filter) and here, the compact scheme with its eighth-order filter seems to have a better spectral accuracy than the considered dispersion-relation preserving scheme with its associated filter, especially in term of dissipation. Secondly, such a coupled space-time approach is applied to the new class of high-order spectral discontinuous approaches, focusing especially on the Spectral Difference method. A new way to address the specific spectral behaviour of the scheme is introduced first for wavenumbers in [0; π], following the Matrix Power method. For wavenumbers above π, an aliasing phenomenon always occurs but it is possible to understand and to control the aliasing of the signal. It is shown that aliasing depends on the polynomial degree and on the number of time steps. A new way to define dissipation and dispersion is introduced and applied to wavenumbers larger than π. Since the new criteria recover the previous results for wavenumbers below π, the new approach is an extension of all the previous ones for analysing dissipation and dispersion. Finally, since the standard Finite Difference schemes can servevas reference solution for their capability in aeroacoustics, it is shown that the Spectral Difference method is as accurate as (or even more accurate) than the considered Finite Difference schemes. }, url = {http://dx.doi.org/10.1016/j.jcp.2017.02.043}}

Bushuk, M., Msadek, R., Winton, M., Vecchi, G. A., Gudgel, R. G., Rosati, A. and Yang, X. (2017) Summer Enhancement of Arctic Sea Ice Volume Anomalies in the September-Ice Zone, Journal of Climate, 30, pp. 2341-2362, doi:10.1175/JCLI-D-16-0470.1

[pdf] [Supplementary Material] [doi]

@ARTICLE{AR-CMGC-17-48, author = {Bushuk, M. and Msadek, R. and Winton, M. and Vecchi, G.A. and Gudgel, R.G. and Rosati, A. and Yang, X. }, title = {Summer Enhancement of Arctic Sea Ice Volume Anomalies in the September-Ice Zone}, year = {2017}, volume = {30}, pages = {2341-2362}, doi = {10.1175/JCLI-D-16-0470.1}, journal = {Journal of Climate}, pdf = {http://cerfacs.fr/wp-content/uploads/2017/03/GlobC-Article-Msadek-Summer-Mars-2017.pdf}, supplementaryMaterial = {http://cerfacs.fr/wp-content/uploads/2017/03/SM-Article-Msadek-Summer-Mars2017.pdf}}

NI, F., Brebion, M., Nicoud, F. and Poinsot, T. (2017) Accounting for Acoustic damping in a Helmholtz Solver, AIAA Journal, doi:10.2514/1.J055248

[pdf] [doi]

@ARTICLE{AR-CFD-17-50, author = {NI, F. and Brebion, M. and Nicoud, F. and Poinsot, T. }, title = {Accounting for Acoustic damping in a Helmholtz Solver}, year = {2017}, doi = {10.2514/1.J055248}, journal = {AIAA Journal}, abstract = { Thermoacoustic Helmholtz solvers provide a cheap and efficient way of predicting combustion instabilities. However, because they rely on the inviscid Euler equations at zero Mach number, they cannot properly describe the regions where aerodynamics may interact with acoustic waves, in the vicinity of dilution holes and injectors, for example. A methodology is presented to incorporate the effect of non-purely acoustic mechanisms into a three-dimensional thermoacoustic Helmholtz solver. The zones where these mechanisms are important are modeled as two-port acoustic elements, and the corresponding matrices, which notably contain the dissipative effects due to acoustic–hydrodynamic interactions, are used as internal boundary conditions in the Helmholtz solver. The rest of the flow domain, where dissipation is negligible, is solved by the classical Helmholtz equation. With this method, the changes in eigenfrequency and eigenmode structure introduced by the acoustic–hydrodynamic effects are captured, while keeping the simplicity and efficiency of the Helmholtz solver. The methodology is successfully applied on an academic configuration, first with a simple diaphragm, then with an industrial swirler, with matrices measured from experiments and large-eddy simulation.}, pdf = {http://cerfacs.fr/wp-content/uploads/2017/03/CFD_AIAAJ_NI_2017.pdf}}

Swingedouw, D., Mignot, J., Ortega, P., Khodri, M., Menegoz, M., Cassou, C. and Hanquiez, V. (2017) Impact of explosive volcanic eruptions on the main climate variability modes, Global and Planetary Change, 150, pp. 24-45, doi:10.1016/j.gloplacha.2017.01.006

[pdf] [doi]

@ARTICLE{AR-CMGC-17-29, author = {Swingedouw, D. and Mignot, J. and Ortega, P. and Khodri, M. and Menegoz, M. and Cassou, C. and Hanquiez, V. }, title = {Impact of explosive volcanic eruptions on the main climate variability modes}, year = {2017}, volume = {150}, pages = {24-45}, doi = {10.1016/j.gloplacha.2017.01.006}, journal = {Global and Planetary Change}, pdf = {http://www.sciencedirect.com/science/article/pii/S0921818116300352}}

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LE CERFACS RECRUTE

Post-doctoral position in computational mechanics

 

  Contexte / Context Domain decomposition methods are well established approaches for solving large scale problems on parallel computers. In the field of solid mechanics, non-overlapping approaches such as FETI (Finite Element Tearing and Interconnecting) and BDD (Balancing Domain Decomposition) are recognized as the methods of choice. Given the current trend of increasing computational power by increasing the number of cores, the adaptation and tuning of these approaches is essential in order to maintain their parallel efficiency while employing large numbers of cores.   Description In domain decomposition methods, the domain associated with the partial differential equation is decomposed into a possibly large number of subdomains. Local problems are then defined on each subdomain and are solved at each iteration step in order to approximate the inverse of the system’s matrix (stiffness matrix in mechanics for instance). It must be noticed that, in order to obtain an efficient and scalable parallel...Lire plus


Thèse (avec CNRM/Météo-France) : Couplage bi-directionnel feu-atmosphère pour des simulations à la demande en cas d'incendies de forêt

 

Financement : Projet FireCaster financé par l'Agence Nationale de la Recherche () en collaboration avec plusieurs partenaires académiques français dont CNRM/Météo-France, CNRS/Cerfacs.   Sujet : La modélisation couplée feu-atmosphère constitue un axe de recherche important avec des finalités opérationnelles dans la prévision de la propagation des feux de forêt. Dans ce cadre, un couplage entre le modèle de recherche atmosphérique Méso-NH () et le modèle de propagation de feux ForeFire () a été développé depuis plusieurs années. Voir l'exemple du feu d'Aullène en Corse en 2009 : Le modèle Méso-NH est basé sur l'approximation anélastique, c'est-à-dire que les équations de l'atmosphère sont discrétisées autour d'un état de référence hydrostatique stationnaire, dont on néglige les variations horizontales et temporelles de la densité de l'air. Cette hypothèse présente des limitations fortes dans la simulation des feux de forêt, où les dégagements de chaleur très importants induisent des variations horizontales et temporelles de la...Lire plus

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