Behavior of heavy particles in isotropic turbulence.

The motion of heavy particles in isotropic turbulence is investigated using direct numerical simulation. The statistics related to the velocity and acceleration of heavy particles for a wide range of Stokes numbers, defined as the ratio of the particle response time to the Kolmogorov time scale of turbulence (St=tau_{p}/tau_{eta}) , are investigated. A particular emphasis is placed on the statistics of the fluid experienced by heavy particles, which provide essential information on the dispersion of these particles. The integral time scale of the velocity correlation of fluid seen by the particles T_{f} , which determines the diffusivity of heavy particles, displays a complex behavior different from the Lagrangian integral time scale of fluid T_{L} . A plausible physical explanation for the behavior of the time scale is provided.