ON THE 2-WAY INTERACTION BETWEEN HOMOGENEOUS TURBULENCE AND DISPERSED SOLID PARTICLES .2. PARTICLE DISPERSION

Part I of this paper [Elghobashi and Truesdell, Phys. Fluids A 5, 1790 (1993)] examined the modulation of turbulence by the particles. Here the effects of the two-way interaction on particle dispersion are discussed. In zero gravity, the two-way coupling enhances the alignment of the surrounding fluid velocity vector with the direction of the solid particle trajectory. This alignment reduces the mean-square relative velocity and increases the Lagrangian velocity autocorrelation coefficient of the solid particle, the fluid point and the surrounding fluid, and the mean-square displacement of the solid particles. However, the fluid point mean-square displacement decreases because the larger inertia of the solid particles increases the decay rate of turbulence energy. In gravity environment, the particles augment the component of turbulence energy in the gravity direction, and thus increase the mean-square displacement of the solid particles and fluid points in that direction. However, their dispersion in the lateral directions is reduced due to the crossing trajectories effect [Yudine, Adv. Geophys. 6, 185 (1959)].