Abstract: Numerical schemes, turbulence models, and computational mesh are the three main factors that affect the precision of CFD simulation. Mesh adaptation based on the information of flow field has the ability to dynamically optimize the mesh, which is considered by NASA as a vital technique for the development of CFD in the future. Aimed at the unstructured hybrid mesh, three critical techniques, including the distribution optimization of mesh elements, surface mesh projection onto geometry, and volume mesh conformal deformation, are proposed to establish a robust adaptation system with high geometry fidelity. First, the distribution optimization technique based on polyhedral elements with standard faces are developed to improve the robustness and the universality of the adaptation system. Next, the local surface reconstruction method which relies only on the points of surface mesh is developed. The new inserted surface points can be parametrically projected onto the geometry, eliminating the dependency of mesh adaptation on the CAD system. Then, the improved distance function method is adopted to rapidly match the volume mesh elements to the projected surface mesh. Finally, combined with the mesh adaptation based on the flow features detector, the flow simulation with the second order finite volume method is carried out for the 30P30N airfoil and the delta-wing with a large angle of attack. The numerical results show that, after the mesh optimization with mesh adaptation proposed in this paper, both the convergence performance and precision of the flow simulation are significantly improved.

Key words: mesh adaptation, hybrid mesh, refinement and coarsening, surface reconstruction, surface mesh projection, 30P30N airfoil, delta-wing