A conservative momentum-exchange algorithm for interaction problem between fluid and deformable particles

A new method for studying interaction between elastic object and a fluid is developed. The fluid phase including solid interface is solved by our immersed boundary method of body-force type (Kajishima et al., JSME Int. J. Ser. B 2001; 44(4):526-535, Kajishima and Takiguchi, Int. J. Heat Fluid Flow 2002; 23(5):639-646). The method has enabled the simulation of interaction problem between a fluid and rigid spherical particles of a total number of O(10(3)) by an efficient momentum-exchange technique through volume-averaged velocity field of multiple phases. In the present study, the fluid-solid interaction force is incorporated into FEM. This process is done by a superposition of the hydrodynamic force field with the solid internal force field. The uniqueness of the present approach lies in the implementation of the inter-phase momentum exchange through the distributed force field shared by both Eulerian and moving Lagrangian references. The applicability of the present method is demonstrated in two 2-D flow fields including a large number of elastic particles. The effects of particle geometry and elasticity are investigated. The results suggest that particles' neutral geometry and deformability exhibit strong correlation to rotating motions and clustering behaviours of the particles in the fluid flow. Copyright (C) 2010 John Wiley & Sons, Ltd.