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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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NEWS

Continuity of activity of the Cerfacs during the Covid-19 pandemic

superadmin |  20 March 2020

On Monday 16 March 2020, in the context of the rapidly evolving COVID-19 epidemic, Cerfacs decided to reorganize its activities by implementing a Business Continuity Plan (BCP) and deploying teleworking facilities for all its employees. All staff members thus continue to carry out their full mission.Read more


A fiery wakeup call for climate science

superadmin |  26 February 2020

The extent of the recent wildfires in Australia significantly exceeded the projections of any member of the multi-model CMIP archive.  This highlights how current multi-model ensembles may be under-representing the risks of natural disasters under climate change.  Limited coupled system process representation in most models coupled with a lack of parameter uncertainty exploration means that some risks are not explored by the existing international multi-model framework.  This calls for a reassessment of how to focus climate model development on providing robust risk quantification for those impacts which most directly affect society. Sanderson, B.M., Fisher, R.A. A fiery wake-up call for climate science. Nat. Clim. Chang. (2020) nature.com Media coverage BBC Sydney Morning Herald The Guardian Wired The Daily Express YahooRead more

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CALENDAR

RESEARCH PUBLICATIONS

Boé, J., Somot, S., Corre, L. and Nabat, P. (2020) Large discrepancies in summer climate change over Europe as projected by global and regional climate models: causes and consequences, Climate Dynamics, 54, pp. 2981–3002, doi:10.1007/s00382-020-05153-1

[doi]

@ARTICLE{AR-CMGC-20-29, author = {Boé, J. and Somot, S. and Corre, L. and Nabat, P. }, title = {Large discrepancies in summer climate change over Europe as projected by global and regional climate models: causes and consequences}, year = {2020}, volume = {54}, pages = {2981–3002}, doi = {10.1007/s00382-020-05153-1}, journal = {Climate Dynamics}}

Qasmi, S., Cassou, C. and Boé, J. (2020) Teleconnection processes linking the intensity of the Atlantic Multidecadal Variability to the climate impacts over Europe in boreal winter., Journal of Climate, 33, pp. 2681–2700, doi:10.1175/JCLI-D-19-0428.1

[doi]

@ARTICLE{AR-CMGC-20-30, author = {Qasmi, S. and Cassou, C. and Boé, J. }, title = {Teleconnection processes linking the intensity of the Atlantic Multidecadal Variability to the climate impacts over Europe in boreal winter.}, year = {2020}, volume = {33}, pages = {2681–2700}, doi = {10.1175/JCLI-D-19-0428.1}, journal = {Journal of Climate}}

Bauer, M., Silva, G. and Ruede, U. (2020) Truncation errors of the D3Q19 lattice model for the lattice Boltzmann method, Journal of Computational Physics, 405, doi:10.1016/j.jcp.2019.109111

[pdf] [url] [doi]

@ARTICLE{AR-PA-20-8, author = {Bauer, M. and Silva, G. and Ruede, U. }, title = {Truncation errors of the D3Q19 lattice model for the lattice Boltzmann method}, year = {2020}, volume = {405}, doi = {10.1016/j.jcp.2019.109111}, journal = {Journal of Computational Physics}, abstract = {We comment on the truncation error analysis and numerical artifacts of the D3Q19 lattice Boltzmann model reported in Silva et al. [3]. We present corrections for specific spatial truncation error terms in the momentum conservation equations. By introducing an improved discrete equilibrium for the D3Q19 stencil, we show that the reported spurious currents in a square channel duct flow are caused by the form of the discrete equilibrium and are not due to the structure and isotropy properties of the D3Q19 velocity set itself. Numerical experiments on a square channel and a more complex nozzle geometry confirm these results.}, keywords = {A PARAITRE}, pdf = {https://doi.org/10.1016/j.jcp.2019.109111}, url = {https://www.sciencedirect.com/science/article/pii/S0021999119308162}}

Esnault, S., Duchaine, F., Gicquel, L. Y. M. and Moreau, S. (2020) Large Eddy Simulation of heat transfer within a multi-perforation synthetic jets configuration, Journal of Turbomachinery, March (TURBO-20-1005), pp. 1-25 (25 pages), doi:10.1115/1.4046545

[pdf] [doi]

@ARTICLE{AR-CFD-20-33, author = {Esnault, S. and Duchaine, F. and Gicquel, L.Y.M. and Moreau, S. }, title = {Large Eddy Simulation of heat transfer within a multi-perforation synthetic jets configuration}, year = {2020}, number = {TURBO-20-1005}, volume = {March}, pages = {1-25 (25 pages)}, doi = {10.1115/1.4046545}, journal = {Journal of Turbomachinery}, abstract = {Synthetic jets are produced by devices that enable a suction phase followed by an ejection phase. The resulting mean mass budget is hence null and no addition of mass in the system is required. These particular jets have especially been considered for some years for flow control applications. They also display features that can become of interest to enhance heat exchanges, for example for wall cooling issues. Synthetic jets can be generated through different mechanisms, such as acoustics by making use of a Helmholtz resonator or through the motion of a piston as in an experience mounted at Institut Pprime in France. The objective of this specific experiment is to understand how synthetic jets can enhance heat transfer in a multi-perforated configuration. As a complement to this experimental set up, Large-Eddy Simulations are produced and analysed in the present document to investigate the flow behavior as well as the impact of the synthetic jets on wall heat transfer. The experimental system considered here consists in a perforated heated plate, each perforation being above a cavity where a piston is used to control the synthetic jets. Placed in a wind tunnel test section, the device can be studied with a grazing flow and multiple operating points are available. The one considered here implies a grazing flow velocity of 12.8 m.s 􀀀1, corresponding to a Mach number around 0.04, and a piston displacement of 22 mm peak-to-peak at a frequency of 12.8 Hz. These two latter parameters lead to a jet Reynolds number of about 830. A good agreement is found between numerical results and experimental data. The simulations are then used to provide a detailed understanding of the flow. Two main behaviours are found, depending on the considered midperiod. During the ejection phase, the flow transitions to turbulence and the formation of characteristic structures is observed; the plate is efficiently cooled. During the suction phase the main flow is stabilised; the heat enhancement is particularly efficient in the hole wakes but not between them, leading to a heterogeneous temperature field.}, keywords = {Boundary layer development, Computational Fluid Dynamics (CFD), Heat transfer and film cooling}, pdf = {https://cerfacs.fr/wp-content/uploads/2020/03/Esnault_turbo-20-1005.pdf}}

Duchaine, F., Gicquel, L. Y. M., Grosnickel, T. and Koupper, C. (2020) Large-Eddy Simulation of the Flow Developing in Static and Rotating Ribbed Channels, Journal of Turbomachinery, 142 (4), pp. 41003, doi:10.1115/1.4046267

[Supplementary Material] [doi]

@ARTICLE{AR-CFD-20-34, author = {Duchaine, F. and Gicquel, L.Y.M. and Grosnickel, T. and Koupper, C. }, title = {Large-Eddy Simulation of the Flow Developing in Static and Rotating Ribbed Channels}, year = {2020}, number = {4}, volume = {142}, pages = {041003}, doi = {10.1115/1.4046267}, journal = {Journal of Turbomachinery}, abstract = {In the present work, the turbulent flow fields in a static and rotating ribbed channel representative of an aeronautical gas turbine are investigated by the means of wall-resolved compressible large-Eddy simulation (LES). This approach has been previously validated in a squared ribbed channel based on an experimental database from the Von Karman Institute (Reynolds and rotation numbers of about 15,000 and ±0.38, respectively). LES results prove to reproduce differences induced by buoyancy in the near rib region and resulting from adiabatic or anisothermal flows under rotation. The model also manages to predict the turbulence increase (decrease) around the rib in destabilizing (stabilizing) rotation of the ribbed channels. On this basis, this paper investigates in more detail the spatial development of the flow along the channel and its potential impact on secondary flow structures. More specifically and for all simulations, results of the adiabatic static case exhibit two contra-rotating structures that are close to the lateral walls of the channel induced by transversal pressure difference created by the ribs. These structures are generated after the first ribs and appear behind all inter-rib sections, their relative position is partly affected by rotation. When considering the stabilizing rotating case, two additional contra-rotating structures also develop along the channel from the entrance close to the low-pressure wall (rib-mounted side). These vortices are due to the confinement of the configuration, inflow profile and are the result of Coriolis forces induced by rotation. Görtler vortices also appear on the pressure wall (opposite to the rib-mounted side). In the destabilizing rotating case, these two types of secondary structures are found to co-exist, and their migration in the channel is significantly different due to the presence of the ribs on the pressure side. Finally, it is shown that heat transfer affects only marginally the static and stabilized cases while it changes more significantly the flow organization in the destabilizing case mainly because of enhanced heat transfer and increased buoyancy force effects.}, keywords = {CFD, LES, HEAT TRANSFER AND FILM COOLING}, supplementaryMaterial = {https://cerfacs.fr/wp-content/uploads/2020/03/turbo_142_4_041003.pdf}}

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PhD thesis: Exploring an atmospheric plume using a fleet of UAVs

 

Improving our understanding of the fine-scale atmospheric processes (natural with clouds, or induced by anthropogenic activities...Read more


Prediction of pollutants production in aeronautical engines

 

Context The emission of pollutants such as carbon dioxide, nitrogen oxides and soot is a growing...Read more

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