Two/Three Dimensional Dynamic Mesh Moving Method

There are many complex unsteady flow problems including moving boundary, such as aeroelasticity, fluid-structure coupling, multi-body separation problems. The key problem in computational fluid dynamics is the treatment of moving boundary. Computation zone changes over time and the corresponding regional grids need to be updated.The mesh update method including mesh moving and remeshing, mesh moving method only changes the location of the nodes, and maintaining the topological connectivity between nodes. The mesh remeshing is to re-mesh the solution region, it needs to generate the mesh again and map the information from origin mesh to the new one, these two step needs large amount of calculation, and interpolation error is introduced, it is not conducive to the computation in the next step. So, mesh moving method is preferred.In this paper, several major mesh moving method is well studied and improved, in the first part of this paper, research background and recent work of mesh moving method is discussed. In section 2, spring analogy method is analyzed and implemented, and ball-vertex method is introduced briefly. In the case of small deformation, spring analogy method is work well; in the case of large deformation, we use mapping method and elastic solid method. Finite element method is adopted to solve the Laplacian equation, the element mesh moved is used as the computational mesh. Nodes displacements in three coordinate directions were calculated respectively. The displacement of nodes is added to the coordinates of the previous step, then the updated grid is obtained.. By introducing a volume factor, boundaries can be rotated by larger angle without grid overlapping. This method needs to solve n order linear algebraic equations three times, (n is the number of nodes). The elastic analog method needs to solve 3*n order equations. So, the presented method is more efficient than the elastic analog method. Compared with mapping method and spring analogy method, elastic solid method have large amount of computation, but it can deal with large deformation. Elastic solid method includes elastic modulus and Poisson's ratio, so it can control the element shape. Elastic solid method is improved in this paper, the improved method is better than the classical method in the capability of mesh deformation.