Parallelization of Enriched Free Mesh Method for Large Scale Fluid-structure Coupled Analysis

This paper proposes a new treatment for parallel EFMM. EFMM has a shortcoming that is too difficult to apply into adaptive problem or dynamic problem. In the fluid-structure coupled analysis field, these methods are using as a structure analysis method. The new fluid-structure coupled analysis method to solve large-scale fluid-structure interaction problem is already proposed by us. Our new method has nodal consistency at the fluid-structure interface and its calculation efficiency and accuracy are high. SUPG/PSPG stabilized FEM is adopted for fluid analysis, while the high-accuracy analysis method based on EFMM developed by the authors is adopted for structure analysis. EFMM has a feature that can be possible to obtain high accuracy analysis result without high order elements. In short, as the common feature of these methods, it is possible to analyze a fluid or a structure rather accurately by using the first order triangular or tetrahedral elements. In addition, variables are exchanged exactly at the common nodes on the fluid-structure boundary without deteriorating accuracy and calculation efficiency due to the interpolation of variables between nodes. From these features, SUPG/PSPG stabilized FEM and EFMM have a very good chemistry. Therefore, our proposed method can be possible to obtain high accuracy fluid-structure coupled analysis result without high order element. However, our proposed method had a shortcoming that is appeared when it is introduced into parallel method. This shortcoming occurs due to the characteristics of the EFMM. Specifically, parallel efficiency that is very important factor of large-scale analysis will be decrease. Generally, domain decomposition method is certainly needed in the large-scale analysis field. But, usual domain decomposition method will not be able to introduce. Because, making stiffness matrix process by EFMM is different from conventional FEM. Therefore, node data for making stiffness matrix of local element cluster is across some domains. To obtain these data, unnecessary communications will be occurred. By this shortcoming, compatibility of SUPG/PSPG stabilized FEM and EFMM becomes very bad. In view of the large-scale analysis by our proposed method in the near future, this is a very important issue. In order to introduce our proposed method into large-scale parallel analysis, new treatment for parallel EFMM is necessary. Therefore, we propose the new treatment for parallel EFMM and verification of our new treatment and numerical example of fluid-structure interaction computed by our new method are described in this paper.