# CerfacsEnter the world of high performance ...

### Cerfacs in brief

Centre of basic and applied research specialized in modelling and numerical simulation, Cerfacs, through its facilities and expertise in high-performance computing, deals with major scientific and technical research problems of public and industrial interest.

## CECI Contribution to CNRS’ “Petit Illustré” on Complex Systems (CNRS Edition)

ROGEL |  12 October 2017

CECI (Cerfacs, CNRS) and IMFT are both working on numerical modelling of the processes causing river flooding and their uncertainties. A common contribution on this subject, signed by Sophie Ricci and Hélène Roux, appears in Vol. 34 of the "Petit Illustré" collection, edited by CNRS.Read more

## CERFACS was present at the European Researcher Night 2017 at Toulouse

thual |  1 October 2017

"Can we get an engine, an airplane or the entire Earth into a computer?". Such was the catchy title of the CERFACS stand  Friday September 29th, for the "European Research Night" whose theme was "Impossible". A hundred people at the "Quai des Savoirs" in Toulouse took a close interest in the...Read more

### CALENDAR

No event has been found

Mon

06

Nov

Mon

13

Nov

Thu

16

Nov

## From 16 November 2017 to 17 November 2017

### RESEARCH PUBLICATIONS

Coreixas, C., Wissocq, G., Puigt, G., Boussuge, J. -F. and Sagaut, P. (2017) Recursive regularization step for high-order lattice Boltzmann methods, Physical Review E, 96 (3), pp. 033306 (1-22), doi:10.1103/PhysRevE.96.033306
@ARTICLE{AR-CFD-17-140, author = {Coreixas, C. and Wissocq, G. and Puigt, G. and Boussuge, J.-F. and Sagaut, P. }, title = {Recursive regularization step for high-order lattice Boltzmann methods}, year = {2017}, number = {3}, volume = {96}, pages = {033306 (1-22)}, doi = {10.1103/PhysRevE.96.033306}, journal = {Physical Review E}, abstract = {A lattice Boltzmann method (LBM) with enhanced stability and accuracy is presented for various Hermite tensor-based lattice structures. The collision operator relies on a regularization step, which is here improved through a recursive computation of non-equilibrium Hermite polynomial coefficients. In addition to the reduced computational cost of this procedure with respect to the standard one, the recursive step allows to considerably enhance the stability and accuracy of the numerical scheme by properly filtering out second- (and higher-) order non-hydrodynamic contributions in under-resolved conditions. This is first shown in the isothermal case where the simulation of the doubly periodic shear layer is performed with a Reynolds number ranging from $10^4$ to $10^6$, and where a thorough analysis of the case at $Re=3\times 10^4$ is conducted. In the latter, results obtained using both regularization steps are compared against the BGK-LBM for standard (D2Q9) and high-order (D2V17 and D2V37) lattice structures, confirming the tremendous increase of stability range of the proposed approach. Further comparisons on thermal and fully compressible flows, using the general extension of this procedure, are then conducted through the numerical simulation of Sod shock tubes with the D2V37 lattice. They confirm the stability increase induced by the recursive approach as compared with the standard one. }}

Duchaine, F., Dombard, J., Gicquel, L. Y. M. and Koupper, C. (2017) On the importance of inlet boundary conditions for aerothermal predictions of turbine stages with Large Eddy Simulation, Computers and Fluids, 154 (September), pp. 60-73, doi:10.1016/j.compfluid.2017.05.024
@ARTICLE{AR-CFD-17-89, author = {Duchaine, F. and Dombard, J. and Gicquel, L.Y.M. and Koupper, C. }, title = {On the importance of inlet boundary conditions for aerothermal predictions of turbine stages with Large Eddy Simulation}, year = {2017}, number = {September}, volume = {154}, pages = {60-73}, doi = {10.1016/j.compfluid.2017.05.024}, journal = {Computers and Fluids}, abstract = {The analysis of a combustion chamber effects on the aerodynamics and thermal loads applied on a turbine stage is proposed. To do so, an integrated wall-modeled Large-Eddy Simulation of a combustion chamber simulator along with its high pressure turbine stage is performed and compared to a standalone turbine stage computation operated under the same mean conditions. For the standalone stage simulations, a parametric study of the turbulence injected at the turbine stage inlet is also discussed. For this specific configuration and with the mesh resolution used, results illustrate that the aerodynamic expansion of the turbine stage is almost insensitive to the inlet turbulent conditions. However, the temperature distribution in the turbine passages as well as on the stator and rotor walls are highly impacted by these inlet conditions underlying the importance of inlet conditions in turbine stage computations and the potential of integrated combustion chamber/turbine simulations in such a context.}, url = {https://doi.org/10.1016/j.compfluid.2017.05.024}}

Lehner, F., Deser, C. and Terray, L. (2017) Toward a New Estimate of Time of Emergence of Anthropogenic Warming: Insights from Dynamical Adjustment and a Large Initial-Condition Model Ensemble, Journal of Climate, 30, pp. 7739–7756, doi:10.1175/JCLI-D-16-0792.1
@ARTICLE{AR-CMGC-17-146, author = {Lehner, F. and Deser, C. and Terray, L. }, title = {Toward a New Estimate of Time of Emergence of Anthropogenic Warming: Insights from Dynamical Adjustment and a Large Initial-Condition Model Ensemble}, year = {2017}, volume = {30}, pages = {7739–7756}, doi = {10.1175/JCLI-D-16-0792.1}, journal = {Journal of Climate}, pdf = {http://cerfacs.fr/wp-content/uploads/2017/09/GLOBC-Article-Lehner_et_al_JCLIM_2017.pdf}, supplementaryMaterial = {http://cerfacs.fr/wp-content/uploads/2017/09/GLOBC-Article-2017Lehner_et_al_JCLIM_SI.pdf}}

Craig, A., Valcke, S. and Coquart, L. (2017) Development and performance of a new version of the OASIS coupler, OASIS3-MCT 3.0, Geoscientific Model Development, 10, pp. 3297-3308, doi:10.5194/gmd-10-3297-2017
@ARTICLE{AR-CMGC-17-148, author = {Craig, A. and Valcke, S. and Coquart, L. }, title = {Development and performance of a new version of the OASIS coupler, OASIS3-MCT 3.0}, year = {2017}, volume = {10}, pages = {3297-3308}, doi = {10.5194/gmd-10-3297-2017}, journal = {Geoscientific Model Development}, pdf = {http://cerfacs.fr/wp-content/uploads/2017/09/GLOBC-Article-craig-gmd-10-3297-2017.pdf}}

Lunet, T., Lac, C., Auguste, F., Visentin, F., Masson, V. and Escobar, J. (2017) Combination of WENO and Explicit Runge–Kutta Methods for Wind Transport in the Meso-NH Model, Monthly Weather Review, 145 (9), pp. 3817-3838, ISSN 0027-0644; eISSN: 1520-0493
@ARTICLE{AR-PA-17-149, author = {Lunet, T. and Lac, C. and Auguste, F. and Visentin, F. and Masson, V. and Escobar, J. }, title = {Combination of WENO and Explicit Runge–Kutta Methods for Wind Transport in the Meso-NH Model}, year = {2017}, number = {9}, volume = {145}, pages = {3817-3838}, issn = {0027-0644; eISSN: 1520-0493}, journal = {Monthly Weather Review}, abstract = {This paper investigates the use of the weighted essentially nonoscillatory (WENO) space discretization methods of third and fifth order for momentum transport in the Meso-NH meteorological model, and their association with explicit Runge–Kutta (ERK) methods, with the specific purpose of finding an optimal combination in terms of wall-clock time to solution. A linear stability analysis using von Neumann theory is first conducted that considers six different ERK time integration methods. A new graphical representation of linear stability is proposed, which allows a first discrimination between the ERK methods. The theoretical analysis is then completed by tests on numerical problems of increasing complexity (linear advection of high wind gradient, orographic waves, density current, large eddy simulation of fog, and windstorm simulation), using a fourth-order-centered scheme as a reference basis. The five-stage third-order and fourth-order ERK combinations appear as the time integration methods of choice for coupling with WENO schemes in terms of stability. An explicit time-splitting method added to the ERK temporal scheme for WENO improves the stability properties slightly more. When the spatial discretizations are compared, WENO schemes present the main advantage of maintaining stable, nonoscillatory transitions with sharp discontinuities, but WENO third order is excessively damping, while WENO fifth order provides better accuracy. Finally, WENO fifth order combined with the ERK method makes the whole physics of the model 3 times faster compared to the classical fourth-order centered scheme associated with the leapfrog temporal scheme.}, keywords = { Cloud resolving models, Large eddy simulations, Numerical analysis/modeling}, pdf = {https://doi.org/10.1175/MWR-D-16-0343.1}}

### APPLICATION DOMAINS

EnergySpaceAeronautics and AutomotiveEnvironment and climate

## Numerical analysis for CFD

CERFACS is developing multiple software for fluid flow, including chemical reactions, plasma, coupled physics. Some of these solvers are heavily used...Read more

## TEST in english

Text in englishRead more