Cerfacs Enter the world of high performance ...

MODEST Challenge

Environment and Security Modelling

The impact of human activities on the environment and security is an important social issue. CERFACS teams have developed in recent years recognized expertise in the field of natural and industrial risks through their contributions to the projects related to the monitoring of the environment and natural resources, natural and industrial sites at risk. This work was undertaken in synergy with CERFACS partners.  The main  activities are:

  • the impact of transportation modes on climate and atmospheric composition;
  • the air quality at regional and global scales;
  • the simulation of forest fire;
  • the simulation and flood forecasting;
  • the study of industrial sites and explosion risks.

The diversity of the studied risks  results in a diversity of objectives (monitoring, alerting, re-analysis, scenario …), spatio-temporal scales (from a few hundred meters to several hundred kilometers), simulation tools (CFD, hydrodynamics, front propagation, aerodynamics) and algorithms to estimate the risk (direct numerical simulation, optimization and assimilation methods, methods for quantifying uncertainties, multi-dimensional code coupling and / or multi-physics ).

The MODEST challenge integrates a strong digital component and mobilizes all CERFACS teams.  The MODEST Challenge is related to the transverse lines of research “Data Assimilation and Optimization“, “Uncertainties” and the application axis “Environment“, “Combustion“, “Aerodynamics” and “Climate“.


The MODEST Challenge aims to develop:

  • innovative methodological tools (modeling at different scales, coupling between physical and chemical processes, code coupling and data assimilation) applied to concrete problems encountered by the CERFACS associate members;
  • applications to the decision aspiring for operational, particularly for air quality, the spread of forest fires and hydrology / hydraulics.


Started in late 2014, the MODEST Challenge enabled the initiation of works in the fields of air quality and hydrology, notably through  European projects (MACC, EoCoE) and national projects (LEFE, SCHAPI, TOSCA) .

Flood forecasting and flood


Multi-dimensionnal 1D/2D hydraulics coupling en hydraulique, with data      assimilation on the Adour.



Modeling and flood forecasting answer a major challenge: managing water resources and natural hazards. At CERFACS, data assimilation methods are implemented to improve the predictive capacity of hydraulic numerical models limited by uncertainties on knowledge of watersheds, meteorological, hydrological and geographical. The DAMP platform enables real-time forecasting of floods from a river hydraulics code. Works multi-dimensional coupling for 1D / 2D hydraulics allow to model complex flows by limiting the cost calculations in order  to meet the operational and industrial constraints.



More about it…


Wildland fire spread and emissions


Corrections of simulated fire front (blue) by the assimilation of aribone observations (gray) to obtain an analyzed front position.


The improvement of real-time forecasting systems for the spread of forest fires and associated emissions paves the way for direct applications on emergency fire risk management and quality management of the regional air and climate scale. The FIREFLY platform, co-developed by CERFACS and the University of Maryland (Dept. of Fire Protection Engineering, USA) is based on a comprehensive set-data assimilation algorithm type Kalman filter, implemented on a model semi-empirical spread of fire front. This system combines parameter estimation (surface wind, humidity and plant fuel properties) and state estimation (the position of the fire front) to improve the prediction of the position of the fire front in real time.




More about it…


Aviation and environment

Evaluation de l'impact des émissions anthropiques


CERFACS assesses the impact of anthropogenic emissions that affect atmospheric chemistry and radiation balance by complex and indirect mechanisms (streaks of water vapor condensation on aerosols, soot particles responsible for the formation of cirrus clouds, emissions ‘nitrogen oxides …) that disrupt the natural cycles, including that of ozonne, which, combined with other chemical cycles, have an impact on the anthropogenic greenhouse effect




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. We acknowledge PRACE for awarding us access to Joliot-Curie (Genci) hosted at CEA/TGCC, FRANCE, Safran Tech and DGAC fundings within the project ATOM, along with the invaluable technical support at...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