HPSF Conference 2025

TRUST is a High Performance Computing thermohydraulic platform for Computational Fluid Dynamics developed at the French Atomic Energy Commission (CEA). This software is designed for massively parallel (MPI) simulations of conduction, incompressible single-phase, and Low Mach Number (LMN) flows with a Weakly-Compressible multi-species solver and compressible multi-phase flows. It is used as the basis for many specialised applications in the nuclear and new energy fields across CEA. The code is being progressively ported to support GPU acceleration (Nvidia/AMD/Intel) thanks to the Kokkos library, as it is one of the demonstrators of the CExA project. In this talk we will go over our experience using Kokkos to progressively port our large code base. We will cover our enabled GPU features and performances. We will mention some of the difficulties we encountered as well as the strategies we had to adopt that sometimes differ from standard good practices due to the specificity of our application.