Alternate method for resolving particle collisions in PRS of freely evolving particle suspensions using IBM

Particle Resolved simulations using the Immersed Boundary Method (IBM) are performed for freely evolving sphere suspensions in the Reynolds number range of [10, 300], solid volume fraction (φ) of [0.1, 0.4] with solid to fluid density ratio of 2, 10 and 100. Collisions between particles are initiated at an inter-particle buffer distance and solved between subsequent fluid time steps using a soft sphere model. Guidelines for permissible buffer distances are developed as a function of solid fraction. Viscous damping effects in the unresolved thin lubrication layer between particles near collision is modeled using a wet coefficient of restitution. Finally, a new correlation for particle fluctuating velocities is proposed and the predicted drag force is compared to previously proposed drag correlations.