DISPLACEMENT AND PRESSURE TRANSFER BETWEEN STRUCTURAL AND FLUID MESHES IN FLUID-STRUCTURE INTERACTION

摘要

Nonlinear, time-domain hydroelastic analysis of flexible offshore structures requires that the structural motion be transferred to the fluid model and the resulting fluid pressure at the fluid-structure interface be transferred from the fluid model to the structure. When the structural mesh and the fluid mesh describe two distinct three-dimensional surfaces, the transfer of displacement and pressure is both difficult and non-unique. In this paper, a new transfer strategy based on the variational-based smoothing element analysis (SEA) technique is presented. The displacement transfer uses the original formulation of the SEA method, although the application of the procedure to displacement transfer is new. For energy conservation during the reverse pressure transfer, the original functional in the SEA method is enhanced with a new term that attempts to conserve the work done by the hydrodynamic forces when obtaining the global structural nodal forces. To evaluate the transfer methodology, the hydrodynamic response of three rigid bodies are considered. Pressure contours, hydrodynamic coefficients, and motions that are calculated based on the data transferred with the proposed method are compared with the results that are obtained from standard rigid-body hydrodynamics theory that does not include a structural finite element model. The method is shown to work very well. In addition, it has general applicability and it can deal with relatively large geometric differences in the meshes.