Multilayer Resuspension of Small Identical Particles by Turbulent Flow

ABSTRACT

A model for the resuspension of a multilayer deposit by turbulent flow is developed. The resuspension rate is obtained by solving a set of coupled, first-order kinetic equations. The multilayer resuspension rate depends explicitly on single-particle resuspension rates that are determined from a modified energy-transfer model. The surface-particle and particle-particle interaction potentials are calculated by a microscopic approach based on the integration of the Lennard-Jones intermolecular interaction potential. The effect of the surface roughness, which leads to a distribution of the adhesive forces, is considered, as well as the energy transfer from the fluctuating part of the turbulent flow to the particle. It is shown that for a geometrical arrangement of deposited particles with a co-ordination number of two (particles stacked on top of each other) particles from the top layers resuspend at lower friction velocities than particles adjacent to the surface. The predicted long-term resuspension rate decays algebraically with exposure time. Calculations are presented for a two-layer deposit of either SnO₂ and Al₂O₃ particles on a stainless steel surface.