Numerical Verification of Large Scale CFD Simulations: One Way to Prepare the Exascale Challenge

The next supercomputers will provide in the next decade the computational power required to perform very large multiphysics and multiscale simulations. One way to prepare the Exascale challenge is to manage uncertainties. Several approximations occur during a numerical simulation from the physical world to the floating point computation. Among these uncertainties, the floating-point arithmetic approximation will be more and more taken into account to perform a rigorous Verification & Validation process. It will also help to explain possible non numerical reproducibility, to optimize the amount of memory for a specified precision on the results and to improve the software development chain. This paper presents an overview of the numerical verification performed at EDF R&D on the CFDTELEMAC-MASCARET software suite.