An Improved Fictitious Domain Method for Simulating Sedimenting Rigid Particle in a Viscous Fluid

Abstract

In this article, the dynamics of particle-particle collisions in a viscous fluid is numerically investigated. An improved fictitious domain–based computational method for a solid-fluid system is developed and a collision strategy for multiple particles is presented. In earlier methods, a repulsive force is applied to the particles when their separation is less than a critical value and depending on the magnitude of this repulsive force, collision of two or more particles may bounce unrealistically. In the present method, when the collision of two or more particles happens, a direct force is added to each particle through Discrete Element Method (DEM) for particle collision. At the same time, a direct-forcing domain method, which is development of the fictitious domain(FD) method, is applied for simulation of multi-particle fluid flows. It employs a discrete δ- function in the form of bi-function to transfer quantities between the Eulerian and Lagrangian nodes as in the immersed boundary method. This method avoids the need to use Lagrange multipliers for imposition of the rigid body motion. Results for motions of several particles in a viscous fluid are presented.