Added Mass Formulation For Fluid-Structure Interaction

Abstract

Fluid-Structure Interaction (FSI) occurs due to interaction of multiple continuum fields. In our daily life, FSI is a common phenomenon. Birds flying in the air, leaves falling off the tree and waving flags are examples of the interaction of a structure with air. The forces of fluid (liquid/gas) that are acting on the structure will deform the adjacent elastic solid structure. The structural deformations are mainly enforced by fluid fields, acoustic fields and external forces. This work aims at demonstrating how variations of geometries' parameters would affect the fluid loading effect in water using COMSOL Multiphysics 4.4 and compared with analytical data. Three-dimensional objects are placed in a water medium. A solid circular cylinder, a solid sphere, and a rectangular cantilever beam are placed in water and the acoustic wave is applied to the objects. More specifically, background acoustic pressure has been used to simulate an incident plane wave which excites the structures in water. Additionally, the inlet velocity and an outlet pressure are applied for fluid structure interaction investigation. When a structure is placed in water, the interaction between them plays an important role in determining the amount of fluid loading mass. The calculated results of added mass of the common geometry shapes match well with the analytical calculations and the discrepancy behavior of added mass amount due to the establishment of variation of geometries' parameters. More specifically, this research introduces an added mass effect study for fluid structure interaction while a specific micro electro mechanical system is submerged in water medium. Subsequently, based on the mentioned studies, an added mass formulation is derived for a specific MEMS (Micro Electro Mechanical System).