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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.

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First 360-degrees Large-Eddy Simulation of a full engine

Jérôme DOMBARD |  17 June 2020

Within the PRACE project FULLEST (First fUlL engine computation with Large Eddy SimulaTion), a joint collaboration between CERFACS, SAFRAN and AKIRA technologies, Dr. C. Pérez Arroyo (post doctoral fellow at CERFACS) has carried out under the supervision of Dr. J. Dombard the first high-fidelity simulation of a part of the real engine DGEN380 (for now, from the fan to the combustion chamber). This 360-degrees integrated large-eddy simulation contains around two billion cells on the three instances, carried out with the AVBP code of CERFACS.  The CPU cost is obviously large but still within reach, performing around one turn of fan during 5 days over 14400 skylake cores. Post-treatments are in progress and already show, among other complex phenomena, a strong interaction between the high pressure compressor and the combustion chamber (see forthcoming paper GT2020-16288 C. Pérez Arroyo et al). Below a video showing: in the fan an isosurface at mid-height of the vein colored by the Mach number, in the high pressure compressor a gradient of density, in the bypass of the combustion chamber the static pressure and in the flame tube a temperature field. One of the goals of the project is to create a high-fidelity unsteady database to study interactions between modules and may help other teams to develop new lower order models and/or validate existing ones. Beyond the feasibility and the maturity of the AVBP code, this kind of calculation is an important milestone for the aeronautical industry and would allow to apprehend earlier in the design the effect of integration and installation and thus, to reduce the cycle and therefore the cost of the future aircraft engines. PRACE and GENCI CPU ressources and Safran Tech/DGAC fundings are gratefully acknowledged, along with the invaluable technical support at CERFACS: Dr. G. Staffelbach, Dr. F. Duchaine, Dr. L. Gicquel, Dr....Read more


B. Cuenot distinguished as Program Chair of international Symposium on Combustion

superadmin |  29 May 2020

B. Cuenot has been distinguished as Program Chair for the 39th International Symposium on Combustion, to be held in Vancouver (Canada) in 2022. The International Symposium on Combustion is a major event for the combustion community, where the current best research is presented.Read more

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RESEARCH PUBLICATIONS

Dosio, A., Turner, A. G., Tamoffo, A. T., Sylla, M. B., Lennard, C., Jones, R. G., Terray, L., Nikulin, G. and Hewitson, B. (2020) A tale of two futures: contrasting scenarios of future precipitation for West Africa from an ensemble of regional climate models, Environmental Research Letters, 15 (6), pp. 64007, doi:101088/1748-9326/ab7fde

[pdf] [doi]

@ARTICLE{AR-CMGC-20-65, author = {Dosio, A. and Turner, A.G. and Tamoffo, A.T. and Sylla, M.B. and Lennard, C. and Jones, R.G. and Terray, L. and Nikulin, G. and Hewitson, B. }, title = {A tale of two futures: contrasting scenarios of future precipitation for West Africa from an ensemble of regional climate models}, year = {2020}, number = {6}, volume = {15}, pages = {064007}, doi = {101088/1748-9326/ab7fde}, journal = {Environmental Research Letters}, pdf = {https://cerfacs.fr/wp-content/uploads/2020/06/Globc-Article-Dosio_2020_Environ._Res._Lett._15_064007-2020.pdf}}

Roy, P., Jofre, L., Jouhaud, J. -C. and Cuenot, B. (2020) Versatile Sequential Sampling Algorithm using Kernel Density Estimation, European Journal of Operational Research, 284 (1), pp. 201-211, doi:10.1016/j.ejor.2019.11.070

[doi]

@ARTICLE{AR-CFD-20-18, author = {Roy, P. and Jofre, L and Jouhaud, J.-C. and Cuenot, B. }, title = {Versatile Sequential Sampling Algorithm using Kernel Density Estimation}, year = {2020}, number = {1}, volume = {284}, pages = { 201-211}, doi = {10.1016/j.ejor.2019.11.070}, journal = {European Journal of Operational Research}, abstract = {Understanding the physical mechanisms governing scientific and engineering systems requires performing experiments. Therefore, the construction of the Design of Experiments (DoE) is paramount for the successful inference of the intrinsic behavior of such systems. There is a vast literature on one-shot designs such as low discrepancy sequences and Latin Hypercube Sampling (LHS). However, in a sensitivity analysis context, an important property is the stochasticity of the DoE which is partially addressed by these methods. This work proposes a new stochastic, iterative DoE – named KDOE – based on a modified Kernel Density Estimation (KDE). It is a two-step process: (i) candidate samples are generated using Markov Chain Monte Carlo (MCMC) based on KDE, and (ii) one of them is selected based on some metric. The performance of the method is assessed by means of the C2-discrepancy space-filling criterion. KDOE appears to be as performant as classical one-shot methods in low dimensions, while it presents increased performance for high-dimensional parameter spaces. It is a versatile method which offers an alternative to classical methods and, at the same time, is easy to implement and offers customization based on the objective of the DoE.}, keywords = {Stochastic processes, Design of experiments, Discrepancy, Optimal design, Uncertainty quantification}}

Schiemann, R., Athanasiadis, P. J., Barriopedro, D., Doblas-Reyes, F., Lohmann, K., Roberts, M. J., Sein, D. V., Roberts, C. D., Terray, L. and Vidale, P. L. (2020) Northern Hemisphere blocking simulation in current climate models: evaluating progress from the Climate Model Intercomparison Project Phase 5 to 6 and sensitivity to resolution, Weather and Climate Dynamics, 1, pp. 277-292, doi:10.5194/wcd-1-277-2020

[pdf] [Supplementary Material] [doi]

@ARTICLE{AR-CMGC-20-61, author = {Schiemann, R. and Athanasiadis, P.J. and Barriopedro, D. and Doblas-Reyes, F. and Lohmann, K. and Roberts, M.J. and Sein, D.V. and Roberts, C.D. and Terray, L. and Vidale, P.L. }, title = {Northern Hemisphere blocking simulation in current climate models: evaluating progress from the Climate Model Intercomparison Project Phase 5 to 6 and sensitivity to resolution}, year = {2020}, volume = {1}, pages = {277-292}, doi = {10.5194/wcd-1-277-2020}, journal = {Weather and Climate Dynamics}, pdf = { https://wcd.copernicus.org/articles/1/277/2020/wcd-1-277-2020.pdf}, supplementaryMaterial = {https://wcd.copernicus.org/articles/1/277/2020/wcd-1-277-2020-supplement.pdf}}

Lo Schiavo, E., Laera, D., Riber, E., Gicquel, L. Y. M. and Poinsot, T. (2020) Effects of liquid fuel/wall interaction on thermoacoustic instabilities in swirling spray flames, Combustion and Flame, 219 (september), pp. 86-101, doi:10.1016/j.combustflame.2020.04.015

[url] [doi]

@ARTICLE{AR-CFD-20-62, author = {Lo Schiavo, E. and Laera, D. and Riber, E. and Gicquel, L.Y.M. and Poinsot, T. }, title = {Effects of liquid fuel/wall interaction on thermoacoustic instabilities in swirling spray flames}, year = {2020}, number = {september}, volume = {219}, pages = {86-101}, doi = {10.1016/j.combustflame.2020.04.015}, journal = {Combustion and Flame}, abstract = {Computational prediction of thermoacoustic instabilities arising in gas turbine and aero-engine combustors still remains a challenge especially if fuel is injected in a liquid spray form. This study shows that, in LES of such a combustor, the treatment of the liquid fuel film created on the walls of the injection system affects the mean flame weakly, but modifies the flame dynamics strongly. The configuration used for this work is the experimental setup SICCA-spray available at EM2C laboratory in Paris. First steady spray flame measurements are used to validate the LES Euler-Lagrange approach. Two modelling strategies for the interaction between the liquid fuel and the injector walls are tested with a negligible impact on the flame shape and structure. In the second part the same comparison is applied to another operating condition where a self-sustained thermo-acoustic limit-cycle is experimentally observed. In that case resonant coupling is achieved with LES, confirming the adequacy of the approach but only when the film layer is taken into account. Indeed, contrarily to the stable configuration, the difference between the two Lagrangian boundary conditions is shown to have a major impact on the feedback mechanism leading to the thermoacoustic oscillation.}, keywords = {Thermoacoustic instabilities, Combustion modelling, Two-phase flows, LES, Liquid/wall interaction}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0010218020301590?via%3Dihub}}

Masset, P. -A. and Wissocq, G. (2020) Linear hydrodynamics and stability of the discrete velocity Boltzmann equations, Journal of Fluid Mechanics, 897 (A29), pp. 1-54, doi:10.1017/jfm.2020.374

[doi]

@ARTICLE{AR-CFD-20-63, author = {Masset, P.-A. and Wissocq, G. }, title = {Linear hydrodynamics and stability of the discrete velocity Boltzmann equations}, year = {2020}, number = {A29}, volume = {897}, pages = {1-54}, doi = {10.1017/jfm.2020.374}, journal = {Journal of Fluid Mechanics}, abstract = {The discrete velocity Boltzmann equations (DVBE) underlie the attainable properties of all numerical lattice Boltzmann methods (LBM). To that regard, a thorough understanding of their intrinsic hydrodynamic limits and stability properties is mandatory. To achieve this, we propose an analytical study of the eigenvalues obtained by a von Neumann perturbative analysis. It is shown that the Knudsen number, naturally defined as a particular dimensionless wavenumber in the athermal case, is sufficient to expand rigorously the eigenvalues of the DVBE and other fluidic systems such as Euler, Navier–Stokes and all Burnett equations. These expansions are therefore compared directly to one another. With this methodology, the influences of the lattice closure and equilibrium on the hydrodynamic limits and Galilean invariance are pointed out for the D1Q3 and D1Q4 lattices, without any ansatz. An analytical study of multi-relaxation time (MRT) models warns us of the errors and instabilities associated with the choice of arbitrarily large ratios of relaxation frequencies. Importantly, the notion of the Knudsen–Shannon number is introduced to understand which physics can be solved by a given LBM numerical scheme. This number is also shown to drive the practical stability of MRT schemes. In the light of the proposed methodology, the meaning of the Chapman–Enskog expansion applied to the DVBE in the linear case is clarified.}, keywords = {kinetic theory, computational methods, Navier–Stokes equations}}

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Impact of climate change on clear air turbulence for aviation

 

Context: In the context of the CERFACS / AIRBUS / Météo-France collaboration and the "Climate and...Read more


Numerical simulation of metal particle combustion

 

Context: Metal powder is a very energetic material, which may be used as a fuel. However...Read more

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