Resuspension of small particles from multilayer deposits in turbulent boundary layers

• A hybrid stochastic multilayer resuspension model is developed.
• Influence of layer coverage and particle size distribution on multilayer resuspension is considered.
• We consider the influence of layer thickness on the resuspension along with the spread of adhesion within layers.
• We consider the statistics of non-Gaussian versus Gaussian removal forces including their timescale which plays a crucial and influential role in multilayer resuspension.
• Model predictions are compared with experiments.

This paper describes a hybrid kinetic model for the resuspension of micron-size particles from multilayer deposits in a fully developed turbulent boundary layer. The rate of removal of particles from any given layer depends upon the rate of removal of particles from the layer above which acts as a source of uncovering and exposure of particles to the resuspending flow. The primary resuspension rate constant for an individual particle within a layer is based on the Rock'n'Roll (R'n'R) model using non-Gaussian statistics for the aerodynamic removal forces acting on the particles (Zhang et al., 2013). The coupled layer equations that describe multilayer resuspension of all the particles in each layer are based on the generic lattice model of Friess & Yadigaroglu (2001) which is extended here to include the influence of layer coverage and particle size distribution. The model is used to investigate a range of effects, including the influence of layer thickness on resuspension, the spread of inter-particle adhesive forces within layers, Gaussian and non-Gaussian pdfs for the removal forces and the associated timescales. Finally model predictions are compared with data from two resuspension experiments – STORM (Castelo et al., 1999) and BISE (Alloul-Marmor, 2002).