A Lagrangian Stochastic Model for Heavy Particle Deposition.

A Lagrangian stochastic model for the deposition of heavy particles from turbulent flows is presented. Heavy particles are treated as tracer particles moving in a virtual fluid having heavy particle velocity statistics. These velocity statistics are deduced from the particle momentum equation. The model satisfies the well-mixed condition for this virtual fluid and is consistent with similarity theory. Model agreement with experimental data for the "inertia-moderated" regime and the upper half of the "diffusion-impaction" regime (nondimensional particle relaxation time, tau+p > 5) is excellent. In accord with the results of direct numerical simulations for the diffusion-impaction regime, the model predicts a build-up of particle concentration in the viscous sublayer. Such a build-up concentration is not predicted by current Lagrangian stochastic models nor by models utilizing the "diffusion/free-flight" concept. Copyright 1999 Academic Press.