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Code Coupling and User Interface


CERFACS has a strong expertise in the development and use of generic code coupling libraries.The couplers developed at CERFACS are daily used to address complex scientific problems such as:

Chemistry-Atmosphere coupling with OASIS

Chemistry-Atmosphere coupling with OASIS

  • earth system modelisation for climate science
  • multiphysics coupling (heat transfer, fluid/structure interaction …)
  • multi-composant coupling
  • data assimilation
  • multidisciplinary optimization

All these applications rely on the integration of different solvers that interact at different levels between each others following coupling algorithms.


OASIS and OpenPALM couplers are used to make modular and evolutive coupled applications in a user friendly way. The domains of applications go from many types of research fields to industrial uses.

Any type of code can be coupled with different languages (Fortran, C, C++, Python, Perl, R, …) and type of parallelization (from mono-processor to massively parallel). Coupling of commercial solvers is performed thanks to TCP/IP protocols through user defined functions.

Both coupling libraries provide interpolation functionalities when quantities to exchanges are discretized on different meshes. In OASIS, the interpolation is dedicated to geophysical applications while OpenPALM provide a more generic interpolation framework based on an unstructured mesh formalism thanks to the CWIPI library developed by ONERA.

Both OASIS and OpenPALM runs on high performance computers where computation times as well as parallel data exchanges are optimized in order to not penalize the speed up of massively parallel codes.

ESCAPADE project with OpenPALM

ESCAPADE project with OpenPALM

Associated with the Graphical User Interface generator OpenTea, OASIS and OpenPALM are daily used by Cerfacs and its partners involving academic laboratories as well as industrial companies. OASIS and OpenPALM are distributed under the OpenSource license LGPL.

About two training per year are proposed for Oasis and OpenPalm. OASIS and OpenPALM are still under development following users’ requests as well as optimizations and bug corrections. The funding of these actions rely on different collaborations through industrial, national or european projects.


NextSim General Assembly and TC meeting

CERFACS |  16 September 2021

The General Assembly and TC Meeting took place on 15-16 September 2021. 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

Sophie Valcke from Cerfacs co-authored a new book on atmosphere-ocean modelling

CERFACS |  18 August 2021

new book "Atmosphere-Ocean Modelling - Couling and Couplers” by Prof. Carlos R Mechoso, Prof. Soon-Il An and Dr Sophie Valcke has just been published by World Scientific. The present book fills a void in the current literature by presenting a basic and yet rigorous treatment of how the models of the atmosphere and the ocean are put together into a coupled system. Details are available at  Abstract: Coupled atmosphere-ocean models are at the core of numerical climate models. There is an extraordinarily broad class of coupled atmosphere-ocean models ranging from sets of equations that can be solved analytically to highly detailed representations of Nature requiring the most advanced computers for execution. The models are applied to subjects including the conceptual understanding of Earth’s climate, predictions that support human activities in a variable climate, and projections aimed to prepare society for climate change. The present book fills a void in the current literature by presenting a basic and yet rigorous treatment of how the models of the atmosphere and the ocean are put together into a coupled system. The text of the book is divided into chapters organized according to complexity of the components that are coupled. Two full chapters are dedicated to current efforts on the development of generalist couplers and coupling methodologies all over the worldRead more