TURBULENT DISPERSION OF PARTICLES - THE STP MODEL

A mathematical description of the stochastic transport of particles (S TP) model for particle dispersion in turbulent flows is presented. The STP model is based on established theories of stochastic process mode ling. The parameters of the model include physical properties of the p article (diameter and mass) and a description of the turbulent charact eristics (mean velocities with root mean square fluctuations and their residence-time correlations) of the fluid phase in which the particle s are dispersed. The model includes no adjustable parameters in the se nse of calibration factors. It is independent of any particular turbul ence model, but estimates of its parameters from information available from the common k-epsilon turbulence model are presented. Elements of the STP model are compared with exact solutions of the diffusion equa tion, alternative dispersion models, and experimental data collected u nder well-defined conditions. The STP model reproduces the exact solut ions when both are based on consistent assumptions. Suggested approxim ated terms in the model also reproduce the experimental data nearly wi thin its error under simple flow conditions. The STP model describes t he origin of more complex behavior (counter-gradient diffusion, for ex ample) and has the potential of describing it if sufficient detail abo ut the gas-phase turbulence is known.