Particle Dispersion and Coherent Fine Scale Eddies in Turbulence

Abstract

Direct numerical simulations of homogeneous isotropic turbulence laden with particles have been conducted to clarify the relationship between particle dispersion and coherent fine scale eddies in turbulence. Dispersion of 106 particles are analyzed for several particle Stokes numbers. The spatial distributions of particles depend on their Stokes number, and the Stokes number that causes preferential concentration of particles is closely related to the time scale of coherent fine scale eddies in turbulence. The influential Stokes number can be derived based on the Burgers' vortex model for coherent fine scale eddies. On the plane perpendicular to the rotating axis of fine scale eddy, number density of particle with Stokes number which is close to the influential Stokes number is low at the center of the fine scale eddy, and high in the regions with high dissipation rate of turbulent kinetic energy around the eddy. The maximum number density can be observed at about 1.5 to 2.0 times the eddy radius on the major axis of the fine scale eddy.

Keywords

• multiphase flow
• particle
• turbulence
• direct numerical simulation
• coherent fine scale eddy