Abstract

We report measurements on the statistics of two particle dispersion, acceleration, and velocity structure functions for tracers and inertial particles. We will especially discuss large, neutrally buoyant and small, heavy particles. The experiments are conducted in the center of von Karmann mixing flows at high Reynolds numbers using direct Lagrangian particle tracking. We will show that single time, single particle statistics are not sensitive to particle inertial for both particles; however, we observed an inertial effect on the two-time, or the two-particle statistics. We will also show that the preferential concentration (increase of the radial distribution function) measured in the center of the apparatus is caused by a decrease of the average particle number density as a function of the distance from the center of the apparatus, which is the statistical stationary point of the flow field. The work has been conducted with Mathieu Gibert and Haitao Xu.