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The activity on uncertainty quantification at CERFACS aims to estimate uncertainties for numerical models requiring large computational resources. We develop environmental risk assessments, data assimilation approaches, probabilistic optimization and coupling improvements for High Performance Computing applications.

At CERFACS, the activity on uncertainty quantification relates to the transversal axis “Data-Driven Modeling” and is at the crossroads of the Environment, Climate, Aerodynamics and Combustion thematic axes. Applications at CERFACS concern flood forecasting, prediction of atmospheric dispersion of pollutants, wildfire propagation, representation of climatic variability and combustion chamber ignition calculations.

The main actions are :

  • Ensemble-based simulations with scalar and functional variables, including dimension reduction strategy
  • Development and evaluation of reduced models for large scale problems
  • Use of reduced models for sensitivity analysis, optimization and data assimilation
  • Development of efficient algorithms for stochastic estimation with solvers of increasing complexity (multi-fidelity, multi-level Monte Carlo/MLMC)

These actions are deployed on the following applications:

  • Development of uncertainty quantification algorithms for real scale computation with efficient, scalable and robust domain decomposition algorithms
  • Development of reduced models for sensitivity analysis and ensemble data assimilation, application in hydraulics and aerodynamics for large uncertain variables
  • Application of reduced models for atmospheric boundary layer simulations in the context of uncertainty quantification, application to micro-scale meteorology and in particular to pollutant dispersion
  • Application of multi-fidelity and MLMC algorithms for industrial computational fluid mechanics, multidisciplinary systems and geosciences.
  • Parametric sensitivity tests of global climate model projections to assess uncertainties in regional and global climate risks
  • Simple climate models to assess data constraints on global climate projection uncertainty




CMIP6 debriefing workshop – May 2021: a stocktaking and foresight exercise that highlighted the major and long-term investment of the CNRM-CERFACS group in the latest climate model intercomparison international exercise

CERFACS |  9 June 2021

The participation of the CNRM-CERFACS group in the international coupled global climate model intercomparison exercise CMIP6 was debriefed on 10 and 11 May. Since the mid-1990s, the various phases of the Coupled Model Intercomparison Project (CMIP), supported by the World Climate Research Programme (WCRP), have enabled climate science to make significant progress, feeding into the IPCC reports, supporting regional climate modelling activities and downstream climate services. On the balance sheet, the participation of CNRM-CERFACS in the extremely demanding CMIP6 exercise has resulted in a large-scale, high-quality contribution in terms of climate simulations, thanks in particular to the strong commitment of researchers and engineers, the quality of support services and national and international collaborations. The activities mainly took place over the period 2013-2020. Initially, the production environment ("workflow") was set up and the coupled climate models were assembled by capitalising on the development of components (atmosphere, ocean and continental surfaces) carried out over the long term. The actual production of simulations was spread over 2018-2020. During the debriefing, perspectives (scientific objectives, model development, organisation) were drawn up with a view to a new participation of CNRM and CERFACS in CMIPRead more

CERFACS Combustion paper on rocket engines selected as Distinguished Paper at the last Int. Symp. on Comb. in Adelaide

CERFACS |  14 April 2021

The paper of C. Laurent 'Heat-release dynamics in a doubly- transcritical LO2/LCH4 cryogenic coaxial jet flame subjected to fuel inflow acoustic modulation’  has been selected at the Distinguished Paper in the Gas Turbine and Rocket Engine Combustion colloquium for the 38th International Symposium on Combustion. This paper authored by Laurent, Staffelbach, Nicoud  and  T. Poinsot  is available here:  describes the first LES of a forced doubly transcritical flame.Read more