Large Scale Analysis of Multiphase Flow Involving Dispersed Components with Deformable Boundaries by a New Immersed Boundary Technique Coupled with VOF and FEM

Abstract

Recent advances in direct numerical simulation (DNS) of multiphase flow involving rigid/elastic solid objects in a single/multiple immiscible fluids are presented. The developed numerical method is based on a combined approach of original immersed‐boundary (IB) technique with volume of fluid (VOF) method and finite element method (FEM). Through a brief theoretical background of our unique IB approach, incorporation of additional aspects for fluid (multiple species of fluids) and solid (elasticity) is explained. The IB‐VOF method is demonstrated in a large‐scale 3‐D flow field including a bubble and rigid particles of total number 432. Characteristic particle behaviours in the bubble‐induced flow is studied in a wide range of conditions for volume fraction and density ratios. The IB‐FEM coupling technique tackles suspension flows with multiple elastic objects in 2‐D flow field. Some particles are observed to be trapped in the wake of the falling particles showing characteristic deformed shapes for different neutral shapes and the respective positions in a cluster. Number density of the elastic particles is found to influence the coherent structure of the flow field. The effects of non‐sphericity and elasticity of particles on particle clustering and lubrication will be discussed.