Multilayer Resuspension of Small Identical Particles by Turbulent Flow

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, firstorder kinetic equations. The multilayer resuspension rate depends explicitly on single-particle resuspension rates that are determined from a modified energytransfer 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 longterm 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.