An improved point selection method for hybrid-unstructured mesh deformation using radial basis functions

Mesh deformation is widely used in the aerodynamic shape optimization and aeroelastic simulations. In hybrid-unstructured grid, mesh deformation becomes difficult due to the complexity of grid topology. In this paper, an efficient mesh deformation technique for hybrid-unstructured grids, based on radial basis functions, has been developed. The principle procedure adopted for this scheme can be divided into two steps. Firstly, a series of radial basis functions are constructed by an interpolation method according to the displacements of moving boundary points. Later, the displacements of all points in the computation domain are determined by the above radial basis function series. In order to improve the efficiency, data reduction should be introduced into the interpolation process. Consequently, a multi-level subspace radial basis function interpolation method based on 'double-edge' greedy algorithm is presented to create an approximate interpolation for all moving boundary points. This method is computationally efficient, preserves orthogonality and have no dependency on the type of flow solver. Typical deformation problems of LANN wing, DLR-f6 wing-body-nacelle-pylon configuration and DLR-F11 high lift configuration with hybrid-unstructured grid are selected as the test cases for demonstration of the current implementation. Results show that the present mesh deformation method has good efficiency and robustness especially for large deformation problems.