Enhancing Performance of High-Speed Engineering Flow Computations: The URANOS Case Study

This paper aims to discuss efforts to enhance the performance of the in-house developed Computational Fluid Dynamics (CFD) solver URANOS. In particular, URANOS-2.0 is presented, an evolution of the 2023 solver release [7], as optimized for pre-exascale architectures. As contemporary European HPC facilities within the current EuroHPC JU panorama utilize distinct GPU architec-tures - primarily AMD and NVIDIA - URANOS-2.0 adopts the OpenACC standard for portability. The latest release, resulting from several tuning and refactoring efforts, demonstrates excellent multi-GPU scalability, achieving strong scaling efficiency of over 80% across 64 compute nodes (256 GPUs) on both LUMI and Leonardo and weak scaling efficiency of about 95% on LUMI and 90% on Leonardo with up to 256 nodes (1024 GPUs). These improvements establish URANOS-2.0 as a leading supercom-puting platform for compressible wall turbulence applications, making it ideal for aerospace and energy engineering tasks in the field of Direct Numerical Simulations (DNS), Wall-Resolved Large Eddy Simulations (WRLES), and the latest Wall-Modeled LES (WMLES). The open-source code is available at https://github.com/uranos-gpu/uranos-gpu.