三维复杂外形的双曲型非结构网格生成方法

Hyperbolic unstructured grid generation method of three-dimensional complex configuration

为了实现棱柱网格的自动化生成,发展了使用双曲型偏微分方程生成棱柱网格的方法。利用网格正交性条件和单元体积约束相结合的双曲偏微分方程,从物面网格向外逐步推进生成棱柱形网格。通过类比结构网格双曲型网格生成方法,在非结构网格局部格点坐标系上建立了双曲型网格生成方程,通过格点有限体积法、迎风格式和隐式的方法离散控制方程,使用GMRES求解器求解线性方程组,进而自动生成棱柱网格。该方法应用于球外形、具有尖锐边缘、深凹高凸的旋成体外形、双椭球外形以及X38复杂飞行器,生成的网格表现出良好的正交性和光滑性,表明本文的方法是成功的。数值仿真结果表明本文的网格适用于气动力热的数值模拟。

In order to alleviate the workload of the mesh-generation, a method of generating prismatic grids for viscous flow simulations using hyperbolic partial differential equations was developed. Traditional hyperbolic structured grid generation method was restated and the new method was expanded based on this. Combining orthogonality of the grid and the cell volume specification, the prismatic grid front was gradually generated away from the body surface. The hyperbolic grid generation equation described in the local grid point coordinate system was used to discretize the equations through the upwind and implicit methods, and GMRES solver was used to solve the linear equations, so as to generate the new front layer. To address the prismatic mesh collisions in recessed cavities, explicit numerical dissipation was added with the assistant of grid sensor functions. And pseudo-Laplacian was used to smooth the grid. This method was applied to complex shapes with sharp edges,deep concave, strictly convex and X38 configuration. And the generated meshes showed excellent orthogonality and smoothness, which indicates that the method in this paper is successful. The prism grid was utilized in the flow solver in order to improve the accuracy and efficiency of simulation. Numerical simulation results were in good agreement with experiments. The method proposed in this paper is suitable and accurate not only for aerodynamic simulation, but also for aerothermal environment simulation.