给出了基于非结构动网格的非定常流动问题的数值模拟方法,重点说明两种动态非结构网格方法的原理以及在非定常流模拟中的算法。一种是基于非结构网格的重叠网格方法,该方法结合了非结构网格方法和重叠网格方法的优点,以物面距为准则参数对网格节点进行分类,进而建立重叠网格的网格间插值关系,通过采用动态非结构重叠网格算法,可以处理多体间具有大幅相对运动的非定常问题。另一种是基于Delaunay图映射的动弹网络方法,该方法首先利用已有网格的边界点生成覆盖整个计算域的Delaunay图;然后建立网格点在图上的一一映射关系,通过Delaunay图来描述边界运动;最后利用映射关系获得新网格点的坐标。本文通过多个数值算例(三维外挂物投放、直升机机身＋旋翼前飞、后缘襟翼大偏角运动以及AGARD445.6机翼气动弹性变形)分别对这两种方法进行了验证,结果表明这些方法在动边界非定常流模拟时具有较高的计算效率和鲁棒性。

Two unstructured grid methods for unsteady flow simulation are presented, whose principles and algorithms in unsteady flow simulation are stressed. One is overset unstructured grid method, which has the advantages of unstructured grid and chimera grid and can handle problems with complex geometries and/or moving bodies. The wall distance of grid node is used as a parameter to classify the nodes and define the interpolation boundary of overset grid. A dynamic overset unstructured grid method is used to deal with the unsteady problems with multi-body moving. The other is dynamic unstructured grid based on Delaunay graph mapping, which can handle unsteady flow problems with body motion and deformation. In the method, a Delaunay graph is first generated using boundary nodes of computational grid and one to one mapping is built between Delaunay graph and the grid. The motion or deformation of body is realized by the moving of Delaunay graph and the new computational grid can be generated efficiently by the mapping. A number of cases(3D store separation, helicopter fuselage-rotor interaction, multi-airfoil with large trailing flap pitching, AGARD445.6 wing aeroelastic deformation)are used to validate the unstructured grid methods. All the results show that those methods are efficient in simulating unsteady problems.