一种分子运动和碰撞双重网格DSMC方法研究

基于非结构网格与直角网格相结合的策略,提出一种分子运动和碰撞双重网格DSMC实现方法。通过分子的位置坐标信息,实现运动网格与碰撞网格信息交互,从而结合非结构网格的贴体性和直角网格易于控制子网格数量的优点,同时提出并实现了基于MCS自适应的动态子网格技术以有效限制分子平均碰撞距离,提高了DSMC方法的通用性和计算精度。通过对超声速圆柱绕流和扩张管道的数值模拟,验证该方法的有效性和高精度性。数值结果表明,本文提出的基于分子运动和碰撞双重网格的DSMC方法提高了流场的分辨率,且通过基于MCS自适应的动态子网格技术,有效地降低了流场的平均碰撞距离,提高了碰撞质量和计算精度。

A DSMC implement method of a hybrid grid of molecular motion and collision

Based on the strategy of combining unstructured grid with Cartesian grid,a double grid DSMC method for molecular motion and collision is proposed.Through the position information of molecules,the contact between the moving grid and the collision grid is established,which combines the body-fitting of an unstructured grid and the advantage of being easy to control the number of subgrids of a Cartesian grid.At the same time,a technique of dynamic self-adaptation subgrids based on MCS is proposed and implemented to improve the applicability and computational accuracy of the DSMC method,which effectively limits the mean collision separation of molecules.The effectiveness and high precision of the DSMC method are verified by numerical simulation of the flow around a supersonic cylinder and an expanding pipeline.Numerical results show that the resolution of the flow field around the supersonic cylinder can be enhanced through the DSMC method based on molecular motion and collision double grids,and the mean collision separation through the self-adaptive dynamic subgrids technique can be effectively reduced,the collision quality and the calculation accuracy can be improved.