Stokes point-particle dynamics and flow structure in stationary isotropic turbulence

Numerical simulation and (stochastic) closure modeling for the dynamics of inertial point particles in turbulence present many challenges beyond those encountered in Lagrangian fluid particle motion, even in regimes where the effects of finite particle size and two-way coupling may be considered small.  In this talk we examine a few fundamental aspects using direct numerical simulations of stationary isotropic turbulence at different Reynolds numbers. The Stokes number (defined as ratio of particle momentum response time to the Kolmogorov time scale) is varied from very small to very large. Datasets examined include the fluid velocity and velocity gradients (hence dissipation rate and enstrophy, which are highly intermittent) evaluated along the Stokes particle trajectories.  Numerical experiments involving filtering the turbulence at different scale sizes are also addressed.  The computations are performed using efficient parallel implementations whose costs are nearly independent of the particle count.