For the efficient finite element wind analysis, using the optimal mesh is the one of the most important factors. The optimal mesh can be obtained when the errors of the solution are distributed uniformly over the entire domain. This paper presents the development of a transition element for flow analysis which has a variable number of mid-side nodes and can be effetively used in the adaptive mesh refinement by connecting the locally refined mesh to the existing coarse mesh through a minimum mesh modification. In the dynamic analysis of flow, the optimal mesh should be changed continuously in accordance with the changing error distribution and the proposed refinement/recovery scheme was found to be very effective for this purpose. The modified superconvergent patch recovery for the variable-node element is presented to estimate a posteriori error of the solution for the adaptive mesh refinement. The boundary conditions of the generated nodes by refinement process are different from those used ordinary finite element method in order to describe the singular point correctly. The numerical examples show that the optimal mesh for the finite element analysis of flow around the structures can be obtained automatically by the proposed scheme.
A new finite element technique to solve the problem of wind and structure interactions is presented. Conventionally, wind analysis is performed on the Eulerian description in which the finite element mesh would not move in accordance with the wind flow. However, it is not the case in wind-structure interaction problems because nodes attached to the surface of structure should move with the displacement of structure. The arbitrary Lagangian-Eulerian (ALE) method treats the mesh and flow independently, and allow the mesh to move. In this study, the analysis domain is divided into regions of the structure, air around the structure and the interface of two regions. To satisfy the compatibility and equilibrium conditions between separated regions and to carry out the efficient analysis, rigid link is used. Also the equation of wind and that of structure are arranged in a single matrix equation. Thus the time consuming iterative solution on the interfaced surface is no longer necessary.
