基于直角叉树切割网格的复杂外形N-S方程数值模拟

Numerical Simulation of Navier-Stokes Equations forComplex Configuration Based on Cartesian Grid

对于粘性绕流的数值模拟,在直角叉树切割网格的基础上,结合三角形非结构网格和矩形结构化网格,利用其各自的优势和特点,提出了一种生成混合杂交网格的思路和方法。在物面附近生成了适合粘性流计算的大长宽比矩形网格,在远场分布直角叉树切割网格,快速离散计算空间。对于复杂的多体问题,采用三角形网格来连接各体网格,并运用网格合并的方法,保证了各网格之间的光滑过渡与连接,提高了网格的质量。针对复杂多段翼型绕流问题,在上述网格基础上,采用B－L代数湍流模型和中心有限体积法,完成了 Navier－Stokes方程(N-S方程)的数值模拟。计算结果表明,网格生成和流场计算都是正确的。

A hybrid grid generation method is presented for numerical analysis of viscous flow. The method combines Cartesian grids with structured grids and triangular meshes to provide great flexibility in discretizing a domain, and utilizes the advantages of unstructured grids and structured grids. We generate the body-fitted rectangle grids on the airfoil surface and the Cartesian grids for the far field. In addition, we regard the triangular meshes as an adhesive to link each part of viscous grids. The grid combination methodology is discussed in Subsection 1. 4, which can smooth hybrid grids and improve the quality of the grids. In Subsection 1. 5, we define a uniform type of data in order to manage and arrange grid data in generating grids and flow calculation. The computational grids are shown in Figs. 1,2,4 and 6 for multielement airfoils, and the numerical simulations of Navier-Stokes equations for these airfoils are carried out. The computational results as shown in Figs. 3, 5 and 7 prove that grid generation and flow calculation are correct and feasible.