elsA-Hybrid: An all-in-one structured/unstructured solver for the simulation of internal and external flows. Application to turbomachinery

This paper reports recent work on the extension of the multi- block structured solver elsA to deal with hybrid grids. The new hybrid-grid solver is called elsA-H (elsA-Hybrid), in which a new unstructuredgrid module has been built within the original elsA CFD system. The implementation benefits from the flexibility of the object-oriented design. The aim of elsA-H is to take advantage of the full potential of structured solvers and unstructured mesh generation by all owing any type of grid to be used within the same simulation process. The main challenge lies in the numerical treatment of the hybrid-grid interfaces where blocks of different type meet. In particular, one must pay attention to the transfer of information across these boundaries, so that the accuracy of the numeric al scheme is preserved and flux conservation is guaranteed. In this paper, we present the numerical approac h that allows us to achieve this. A comparison between the hybrid and the structured-grid methods is also carried out by considering a fully hexahedral multi-block mesh for which a few blocks have been transformed into unstructured. The performance of elsA-H for the simulation of internal flows will be demonstrated on a number of turbomachinery configurations.

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