Particle inertia effects on average drag force of free settling particles

In this paper, free settling of monodisperse particles is studied using particle resolved direct numerical simulations. In simulations, immersed boundary method is used for fluid-particle interactions and particle-particle interactions are obtained using discrete element method. It is observed both velocity fluctuations and particle microstructures can be affected by size of domain for smaller settling Reynolds number and volume fraction of particles. For finite Reynolds number (Re≥10); the variance of fluctuations of particle velocity saturates at some constant value by increasing the domain size. It is observed from simulations that the saturation of velocity fluctuations of settling particles is due to wake-induced interactions between particles.