Development of a new hybrid compressible solver inside the CFD elsA software

Abstract

A new fully integrated environment for compressible ow simulation on structured and unstructured zones coexisting within the same hybrid mesh is presented. This environment originates from the existing elsA a CFD software tool, developed by ONERA and CERFACS for structured grids, and widely used both in industry and research. Some con gurations can not be easily addressed with a fully structured mesh approach. An e cient way to overcome this drawback is to combine structured and unstructured zones in a single hybrid mesh. Structured zones are kept for sake of accuracy in boundary layers, wall clock e ciency and low memory consumption. Unstructured zones enable an easier mesh generation / adaptation process. This paper describes the extension of elsA to unstructured multi-element zones composed of hexahedra, tetrahedra, prisms and pyramids. A key feature is the treatment of structured / unstructured zone interfaces, performed with a mismatched abutting grid interface algorithm. We demonstrate that the Object-Oriented (OO) programming approach is useful and e cient to integrate unstructured data structures and numerical methods into the original software to form a single computational CFD kernel. Software design, numerical algorithm, structured/unstructured block interface treatment, CPU e ciency and parallel scalability, are discussed. Finally, validation examples demonstrating the project status are given.