Generation of three dimensional mixed and unstructured grids and its application in solving Navier-Stokes equations

A method for generating three-dimensional mixed-element-type unstructured grids and its application in simulating viscous flow by solving the Navier-Stokes equations are presented. Pirzadeh's advancing-layer method is modified to generate high-quality mixed prismatic/pyramid/ tetrahedral-element-type unstructured grids in the boundary-layer region, and the traditional advancing-front method is used to construct isotropic tetrahedral grids in the residual flow region. Based on the Spalart-Allmaras one equation turbulence model, three-dimensional Navier-Stokes equations are solved by using a cell-centered finite-volume method. Viscous flow problems around the ONERA M6 wing, a DLR-F4 wing-body configuration and a transport configuration are simulated to verify the correctness and practicability of the methods.