Paticle Motion and Flow Structure in Grid-Generated Turbulence with Columnar Particle Dispersions

Particle motion and flow structure were experimentally investigated in grid-generated turbulence with spherical or columnar particle dispersions. Particle motions were taken by a high-speed video camera and instantaneous streamwise and horizontal velocities were measured using a PIV. The results show that columnar particles fall without clustering in the free-falling particle experiment, whereas spherical particles form clusters during the falling process. Turbulence intensity in the grid-generated turbulence with columnar particle dispersion is larger than that in the turbulence with spherical particle dispersion. It is found by flow visualization that these differences in particle motion and fluid structure are attributed to the irregular horizontal movements and rotation of columnar particles.