Adaptive Mesh Refinement: Hypersonic Flow

Hypersonic flows and flight envelopes present unique challenges in Computational Flow Dynamics. The extreme gradients and shocks can push flow solvers to their limits and resolving the flow features, particularly shock formation, is of paramount importance in obtaining valid converged solutions. In Simcenter STAR-CCM+, you can apply Adaptive Mesh Refinement (AMR) to accurately resolve developing shocks using refinement based on solution gradients.

This tutorial covers hypersonic flow around a simple sphere at Mach 12 and incorporates some unique solver settings designed for hypersonic flows. You use the gradient of Mach number as a user-defined criterion for polyhedral mesh adaption. Physically, this gradient is used to capture the velocity discontinuity—which appears as a shock wave. Cells are refined where the gradient of the Mach number exceeds a certain value.

The outer boundaries are set to free stream boundaries. To reduce the cell count, the hypersonic flow is simulated with a half model—the central plane is set to a symmetry plane boundary. The computational domain is illustrated as follows:



The initial mesh is shown below with the initialized flow solution obtained from grid sequencing:



When the simulation is complete, the mesh is refined around the shock wave:



For the purposes of this tutorial, only one level of mesh refinement is permitted. In practice, for an industrial simulation, you would increase the number of levels of mesh refinement to 2 or 3.