On the Lagrangian turbulent dispersion models based on the Langevin equation

Abstract

A Lagrangian approach is used to describe turbulent two-phase particulate flows. Special attention focuses on a currently used model based on the Langevin equation with instantaneous relative velocity of fluid and particles. A detailed analysis of the model is performed and its drawbacks are discussed. Afterwards, a novel model for particle dispersion in homogeneous turbulence is proposed. It is built on physical arguments quite different from those underlying the previous model: rather than instantaneous relative velocities, averaged characteristics of the motion of solid–fluid particle pairs are considered. The new model accounts for both inertia and external force effects. It is validated by comparison with existing experimental data on particle dispersion in grid turbulence and with large-eddy simulations of homogeneous turbulence.