High skewness tetrahedron meshes and its application on high lift configuration

Structured grids are hard to be generated on high lift configuration of transport airplanes due to geometry irregularity, unstructured grids have the chance of optimizing local mesh quality and timesaving with strong adaptability and automatism in grid generation. With tetrahedron grids and cell centered finite volume discretization, solutions on a trapezoidal three-element high-lift wing obtained with an 3D compressible Reynolds averaged Navier-Stokes code are presented. High aspect ratio meshes are formed by advancing layer methods to simulate viscous effect in boundary layer, surrounding high aspect ratio difficulties, methods of solution gradients reconstruction and slope limiters are discussed, and accurate and affordable schemes for current grids are summarized. In the simulation, flows are assumed to be fully turbulent, Spalart-Allmaras turbulence model coupled with N-S equations are solved on parallel computers, flux conservation are enforced at partition boundary. Integrated and distributed aerodynamics loads are compared with experimental data, lift, drag and pitching moment are shown to be in good agreement, pressure distributions are mostly identical except that on wing tip location, where excessive numerical dissipations are exposed because of wing tip vortex. Three different grids ranging from 466M to 2674M are computed comparatively to study grid convergence at α=11.02°, the close up to test data are shown through grid refinement, but the curve slope is not a linear, which can be attributed to complexity of flows.