Direct numerical simulation of the lift-off of particles in plane Poiseuille flows of Newtonian and Oldroyd-B fluids

摘要

In this paper an engineering correlation for the lift-off of a single and many particles is obtained using the numerical data from two-dimensional simulations. In single particle studies, a particle heavier than the fluid is driven forward on the bottom of a channel by a plane Poiseuille flow. At a certain critical shear Reynolds number the buoyant weight of the particle just balances the upward thrust from the hydrodynamic force. The aim of the calculation is the determination of the critical lift-off condition. In many particle simulations, particles heavier than the fluid are initially placed in a closely packed ordered configuration at the bottom of a periodic channel. The fluid-particle mixture is driven by an external pressure gradient. The particles are suspended or fluidized by lift forces that balance the buoyant weight perpendicular to the flow. A correlation for the average fluid fraction in the particle bed as a function of shear Reynolds number is obtained.