Assessment of adaptive mesh refinement methods for shock boundary layer interaction

Abstract

The work presented in this thesis represents a research into adaptive mesh refinement for shock wave boundary layer interactions of an incident shock wave generated by an 8-degree wedge at M = 2.25. The IUSTI (University of Industrial Thermal Systems in Marseille) wind tunnel provided data for validation as part of the 2010 UFAST SBLI workshop. The study was performed using the commercial software STAR-CCM+. The wind tunnel geometry was split into an inlet and test section in order to reduce the computational requirements. A grid convergence study and turbulence model assessment were performed to identify the best model and resolution. The turbulence models used were Spalart-Allmaras, k-ε realizable and k-ω SST. The streamwise average velocity error obtained in the inlet section with the Spalart-Allmaras and K-ω turbulence models was less than experimental uncertainty. The K-ε turbulence model wall treatment was modified in order to obtain error values below the experimental uncertainly. In the test section, it was found that the optimal resolution was close to 14 × 106 cells. The Spalart-Allmaras turbulence model showed a higher accuracy than the other two models. More accurate results were obtained by modifying the K-ω SST constants, however the accuracy did not improve upon the Spalart-Allmaras results in a fine mesh. Adaptive mesh refinement was carried out to improve the solution of a coarse grid while minimising the cost. Two AMR (Adaptive mesh refinement) studies were carried out, one in a hexahedral mesh and other in a polyhedral mesh. Adaptive mesh refinement in the hexahedral mesh showed similar velocity results to fine mesh solution with a frac-tion of the computational cost, bubble size and position errors were less than the ones obtained in the fine mesh. The polyhedral mesh showed greater velocity errors. The main advantage of this mesh was the computation of the bubble size and position with a higher accuracy than hexahedral meshes.