非结构混合网格上的NS方程求解方法

提出了一套较为通用的,完全自动化的非结构混合网格生成方法.在物面粘性作用区,采用一种改进的推进层方法生成三棱柱形和金字塔形网格;在其他流动区域采用阵面推进方法生成四面体网格.采用一种改进精度的格心有限体积法对三维NS方程进行了求解,在加速收敛措施方面,提出了一种新的当地时间步长取定方法来减小质量较差的网格单元对流场计算稳定性和收敛速度的不利影响.以M6机翼和DLR/F4翼身组合体外形的粘性流场作为数值算例,验证了上述网格生成和流场求解方法的正确性和实用性.

The Application of Mixed Element Type Unstructured Grid in Solving Navier-Stokes Equations

A method for generating three-dimensional mixed element type unstructured grids and its application for viscous flow simulations 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 boundary-layer region,and the traditional advancing-front method is used to construct isotropic tetrahedral grids in the residual flow region.Three-dimensional Navier-Stokes equations are solved by using a cell-centered finite-volume method.A new local time stepping method has been developed to eliminate the adverse influence of grid quality on solve stability and convergence speed.Viscous flow problems around the ONERA M6 wing and DLR-F4 wing-body configuration are simulated to verify the correctness and practicability of the methods presented.