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Sparse Days in Saint-Girons IV

Brigitte Yzel |  29 March 2022

Sparse Days Meeting 2022 🗓️  20-22 June 2022  @ Saint-Girons, France   🌐   Sparse Days 2022 will be held in Saint-Girons, Ariège, from 20-22 June. This enhanced version of Sparse Days is being co-organized by Cerfacs and ENSEEIHT/IRIT. It will be the fourth meeting in Saint- Girons following the tradition of the previous meetings held in 1994, 2003, and 2015. The tradition involves coupling our highly successful annual technical meeting with the ambience and hospitality of this wonderful Pyrenean town which encourages fruitful informal exchanges between participants.    Read more


Press releases on the NextSim EuroHPC project

CERFACS |  9 February 2022

Press talks about the NextSim EuroHPC project. CERFACS is involved in two major points. The first topic is to extend the numerical capabilities of the code to perform scale-resolving simulations of jet noise configurations on exascale supercomputers. The second focus is to exploit data from these simulations by extracting or visualising relevant physical information during the computation. CERFACS is involved in the NextSim project (). The primary objective is to increase the capabilities of Computational Fluid Dynamics tools on extreme-scale parallel computing platforms for aeronautical design. This project has received funding from the European High-Performance Computing Joint Undertaking (JU) under grant agreement N° 956104. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and Spain, France, Germany. This project has received funding from the Agence Nationale de la Recherche (ANR) under grant agreement N° ANR-20-EHPC-0002-02. For more information, please visit Read more

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RESEARCH PUBLICATIONS

Delhaye, S., Fichefet, T., Massonnet, F., Docquier, D., Msadek, R., Chripko, S., Roberts, C., Keeley, S. and Senan, R. (2022) Summertime changes in climate extremes over the peripheral Arctic regions after a sudden sea ice retreat, Weather and Climate Dynamics, 3 (2), pp. 555-573, doi:10.5194/wcd-3-555-2022

[doi]

@ARTICLE{AR-CMGC-22-49, author = {Delhaye, S. and Fichefet, T. and Massonnet, F. and Docquier, D. and Msadek, R. and Chripko, S. and Roberts, C. and Keeley, S. and Senan, R. }, title = {Summertime changes in climate extremes over the peripheral Arctic regions after a sudden sea ice retreat}, year = {2022}, number = {2}, volume = {3}, pages = {555-573}, doi = {10.5194/wcd-3-555-2022}, journal = {Weather and Climate Dynamics}}

Nguyen, M., Boussuge, J. -F., Sagaut, P. and Larroya-Huguet, J. C. (2022) Large Eddy Simulation of a Thermal Impinging Jet using the Lattice Boltzmann Method, Physics of Fluids, 34 (5), pp. 55115, doi:10.1063/5.0088410

[doi]

@ARTICLE{AR-CFD-22-50, author = {Nguyen, M. and Boussuge, J.-F. and Sagaut, P. and Larroya-Huguet, J.C. }, title = {Large Eddy Simulation of a Thermal Impinging Jet using the Lattice Boltzmann Method}, year = {2022}, number = {5}, volume = {34}, pages = {055115}, doi = {10.1063/5.0088410}, journal = {Physics of Fluids}, abstract = {A compressible Hybrid Lattice Boltzmann Method solver is used to perform a wall-resolved Large eddy simulation of an isothermal axisym- metric jet issuing from a pipe and impinging on a heated flat plate at a Reynolds number of 23 000, a Mach number of 0.1, and an impinge- ment distance of two jet diameters. The jet flow field statistics, Nusselt number profile (including the secondary peak), and shear stress profile were well reproduced. The azimuthal coherence of the primary vortical structures was relatively low, leading to no discernible tempo- ral periodicity of the azimuthally averaged Nusselt number at the location of the secondary peak. While local unsteady near-wall flow separa- tion was observed in the wall jet, this flow separation did not exhibit azimuthal coherence and was not found to be the only cause of the thermal spots blue, which lead to the secondary peak in the Nusselt number, as stream-wise oriented structures also played a significant role in increasing the local heat transfer.}}

Lea, D. J., While, J., Martin, M. J., Weaver, A. T., Storto, A. and Chrust, M. (2022) A new global ocean ensemble system at the Met Office: Assessing the impact of hybrid data assimilation and inflation settings, Quarterly Journal of the Royal Meteorological Society, doi:10.1002/qj.4292

[doi]

@ARTICLE{AR-PA-22-48, author = {Lea, D.J. and While, J. and Martin, M.J. and Weaver, A.T. and Storto, A. and Chrust, M. }, title = {A new global ocean ensemble system at the Met Office: Assessing the impact of hybrid data assimilation and inflation settings}, year = {2022}, doi = {10.1002/qj.4292}, journal = {Quarterly Journal of the Royal Meteorological Society}, abstract = {We have developed a global ocean and sea-ice ensemble forecasting system based on the operational FOAM (Forecasting Ocean Assimilation Model) system run at the Met Office. The ocean model NEMO and the CICE sea-ice model run at 1/4° resolution and the system assimilates data using a three-dimensional variational assimilation (3DVar) version of NEMOVAR. This data assimilation (DA) system can perform hybrid ensemble/variational assimilation. A 36 member ensemble of hybrid-ensemble-variational assimilation systems with perturbed observations (values and locations) has been set-up, with each member forced at the surface by a separate member of the Met Office Global-Regional Ensemble Prediction System (MOGREPS-G). The unperturbed member is forced by atmospheric fields from the Met Office operational Numerical Weather Prediction (NWP) deterministic system. The system includes stochastic model perturbations and a Relaxation to Prior Spread (RTPS) inflation scheme. A control run of the system using an ensemble of 3DVars is shown to be generally reliable for sea level anomaly (SLA), temperature and salinity (the ensemble spread being a good representation of the uncertainty in the ensemble mean), although the ensemble is underspread in eddying regions. The ensemble mean gives a 4% reduction in error in SLA compared with the deterministic 3DVar system currently used operationally. The system was tested with different weights for the ensemble component of the hybrid background error covariance matrix and different inflation factors. The best results, in terms of short-range forecast error and ensemble reliability statistics, were obtained with hybrid three-dimensional ensemble variational DA (3DEnVar). The RTPS inflation scheme is shown to be beneficial in producing an appropriate ensemble spread in response to hybrid DA. 3DEnVar with an ensemble hybrid weight of 0.8 leads to a reduction of 20% (5%) in the ensemble mean error for SLA (profile temperature and salinity) compared with an ensemble of standard 3DVars. }}

Nguyen, P. L., Bador, M., Alexander, L. V., Todd, P. L. and Ngo-Duc, T. (2022) More intense daily precipitation in CORDEX-SEA regional climate models than their forcing global climate models over Southeast Asia, International Journal of Climatology, pp. 1-25, doi:10.1002/joc.7619

[url] [doi]

@ARTICLE{AR-CMGC-22-30, author = {Nguyen, P.L. and Bador, M. and Alexander, L.V. and Todd, P.L. and Ngo-Duc, T. }, title = {More intense daily precipitation in CORDEX-SEA regional climate models than their forcing global climate models over Southeast Asia}, year = {2022}, pages = {1-25}, doi = {10.1002/joc.7619}, journal = {International Journal of Climatology}, url = {https://rmets.onlinelibrary.wiley.com/doi/10.1002/joc.7619}}

Agostinelli, P. W., Laera, D., Chterev, I., Boxx, I., Gicquel, L. Y. M. and Poinsot, T. (2022) On the impact of H2-enrichment on flame structure and combustion dynamics of a lean partially-premixed turbulent swirling flame, Combustion and Flame, 241, pp. 112120, doi:10.1016/j.combustflame.2022.112120

[pdf] [doi]

@ARTICLE{AR-CFD-22-36, author = {Agostinelli, P.W. and Laera, D. and Chterev, I. and Boxx, I. and Gicquel, L.Y.M. and Poinsot, T. }, title = {On the impact of H2-enrichment on flame structure and combustion dynamics of a lean partially-premixed turbulent swirling flame}, year = {2022}, volume = {241}, pages = {112120}, doi = {10.1016/j.combustflame.2022.112120}, journal = {Combustion and Flame}, abstract = {Large Eddy Simulation (LES) with Conjugate Heat Transfer (CHT) is used to analyze the impact of H-enrichment on the flame structure and combustion dynamics of a lean partially-premixed turbulent CH/Air swirling flame. Experimentally, the combustor is operated at atmospheric pressure with H fuel fractions of up to 50, by volume. LES-CHT results are compared and validated against time-resolved stereo PIV, OH* chemiluminescence, OH-PLIF imaging and acoustic pressure measurements. In terms of dynamics, for the pure CH and 20 of H enrichment cases, no thermoacoustic oscillation is observed in either the experimental or numerical data. As the fuel fraction of hydrogen is increased, the flame length reduces due to the increase in laminar flame speed and the heat release rate distribution becomes more compact. CHT simulations reveal that H-enrichment leads to higher temperatures at the centerbody tip. At 50 H, in agreement with experiments, LES predicts a bi-modal thermoacoustic oscillation, with two main frequencies corresponding to the quarter and chamber modes of the system. Dynamic Mode Decomposition is performed on the measured OH-PLIF images and LES 3D fields to extract each mode contribution to the overall flame dynamics. It is observed that both modes are characterized by local variations of equivalence ratio, while only the higher frequency (chamber) mode is characterized by vortices periodically detaching from the backplane and the centerbody walls causing a strong periodic wrinkling of the flame front during the thermoacoustic oscillation.}, keywords = {H2-enrichment, Thermoacoustic instabilities, Large eddy simulation, Turbulent flames, Conjugate heat transfer}, pdf = {https://cerfacs.fr/wp-content/uploads/2022/05/On_the_impact_of_H2_enrichment_Preprint_AR_CFD_22_36.pdf}}

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