高效非结构网格变形与流场插值方法

Efficient mesh deformation and flowfield interpolation method for unstructured mesh

非结构动网格在含动边界的非定常流动模拟中应用十分广泛。为了提高网格变形的计算效率和对复杂外形的适用性,发展了高效的K近邻-径向基函数(KNN-RBF)动网格方法。并采用高效的交界面节点一致性方法实现了网格变形的并行化。由于边界的运动和变形形式多种多样,在自主开发的计算流体力学(CFD)程序中实现了动网格的用户自定义函数(UDF)功能模块,可以灵活地设置此类问题中的边界运动。在模拟大变形问题时,采用了全局网格重构的策略对网格质量较差的区域进行处理。提出了快速查找新旧网格最近点的两级KD(K-Dimensional)树方法,并根据最近点在新旧网格间进行流场插值。从而建立了高效健壮的并行流场插值方法。通过对若干算例进行模拟,验证了所发展方法的正确性和健壮性。

Unstructured dynamic mesh is widely applied to the simulation of unsteady flow problems containing boundary motions.To improve the efficiency of mesh deformation as well as the capability of handling complex configurations,an efficient K Nearest Neighbor-Radial Basis Functions(KNN-RBF)mesh deformation method is proposed,along with an efficient method to keep the nodes on zonal boundaries consistent.Due to the various forms of boundary motion and deformation,a User Defined Function(UDF)module is developed in the in-house Computational Fluid Dynamics(CFD)code,and flexible manipulation of boundary motion is available when simulating these problems.When simulating cases with large deformations,aglobal mesh regeneration method is adopted to remedy the regions containing low quality cells.A fast searching of the nearest points between the old mesh and new mesh is realized using the two-level K-Dimensional(KD)tree method,and the interpolation of the flowfiled is accomplished using the nearest points.Thus an efficient and robust interpolation method is developed along with parallel processing.Several cases are simulated to validate the effectiveness and robustness of the proposed method.