## A correlation for the lift-off of many particles in plane
Poiseuille flows of Newtonian fluids

#### N. Patankar, T. Ko, H.G. Choi, D.D. Joseph

#### Abstract:

Choi & Joseph (2000) reported a two-dimensional numerical investigation
of the lift-off of 300 circular particles in plane Poiseuille flows of
Newtonian fluids. We perform similar 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. Pressure
waves corresponding to the waves at the fluid-mixture interface are observed.
During the initial transient, these waves grow, resulting in bed erosion. At
sufficiently large shear Reynolds numbers the particles occupy the entire
channel width during the transient. The particle bed eventually settles to an
equilibrium height which increases as the shear Reynolds number is increased.
Heavier particles are lifted to a smaller equilibrium height at the same
Reynolds number. An engineering correlation for the lift-off of many particles
is obtained from the numerical data. The correlation is used to estimate the
critical shear Reynolds number for lift-off of many particles. The critical
shear Reynolds number for lift-off of a single particle is found to be greater
than that for many particles.

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Last Modified: Monday, 10-Dec-2001 13:47:25 CST