Abstract:
With the steady increase of the power of parallel super-computers, 3D unsteady simulations offer a great potential to study turbulent flows. However, the simulation of highly non-linear phenomena such as turbulence, primary atomization or premixed flames requires very accurate numerical methods and high resolution to capture vortex and interface dynamics. While most direct numerical simulations of turbulent flows are carried out with structured grids or Cartesian-based Adaptive Mesh Refinement, recent advances in numerical methods for tetrahedron-based meshes and parallel mesh adaptation strategies raise the attractiveness of unstructured grids. The use of tetrahedra has two advantages for practical configurations: complex geometries are easily meshed and the mesh is locally more isotropic than Cartesian grids. The first part of the presentation will be focused on the development of highly-efficient dynamic adaptation of tetrahedron-based unstructured grids and on projection methods for low-Mach number flows which can cope with adaptive grids. The proposed methodology, which heavily relies on the remeshing library MMG has been thoroughly optimized to reach good performances with grids of several billion cells on more than 10 000 cores. This dynamic mesh adaptation strategy has been implemented in the YALES2 code and applied to the modeling of turbulent flows in many configurations. In these academic and industrial applications, the local mesh adaptation enabled a drastic reduction of the CPU cost compared to the fixed-grid approach and enabled to reach unprecedented mesh resolutions. The second part of the presentation will be dedicated to the efforts to port these methodologies to GPUs while continuing promoting fast development and innovation from a community of non-GPU experts.
LEGI – UMR 5519 – Grenoble