Piotr Szaltys, ZA, MEiL, PW. High-order hybrid grid generation for simulation of high-Reynolds number flows

High-order hybrid grid generation for simulation of high-Reynolds number flows

One of the topic which recently receives much attention in CFD community is related  to the  high-order  (HO) flow simulation. Still  an  important  factor  limiting wider application of HO methods is the lack of robust HO mesh generation methods. This is especially true in the case of turbulent RANS simulations, where high resolution of the boundary layer (BL) is necessary. In this presentation authors introduce an approach to the problem of HO hybrid grid generation, which is focused on creation of valid, thin and curved elements, present in BL region. In the standard approach, the generator first creates a linear grid, next the grid is enriched by adding new internal HO nodes. Finally such a grid is deformed to conform to the curvilinear boundary. The current algorithm consists of two phases: generation of structured BL grid and second, filling remaining space with unstructured grid. Important modification related to the standard approach lies in the creation of the BL grid. This grid possess the same number of DOFs as the final HO BL grid, or in other words, it corresponds to the grid subdivided into HO sub-cells. Thanks to this approach, the thin structured cells in the BL already fits well to the curved boundary surface. Deformation is only applied to the unstructured grid which is used to fill remaining space. Since the cells outside the BL are significantly less stretched then inside the BL, such process becomes more robust then standard one. HO order grids generated using presented approach for 2D and 3D testcases (e.g. Onera M6 wing) will be shown together with simulations obtained using the HO solver PADGE developed in DLR. The presented work is continuation of the work started in the frame of the IDIHOM project.