Multiscale analysis of particle-laden turbulence with gravitational settling

The dynamics of inertial heavy particles in three-dimensional homogeneous isotropic turbulence are investigated, both with and without gravitational settling. To this end direct numerical simulation flow data over a range of Stokes numbers (0.05 ≤ St ≤ 5) and at a Taylor-microscale Reynolds number Re_λ = 204 are analyzed. Utilizing a modified Voronoi tessellation, the divergence, curl, and helicity of particle velocities are computed to quantify clustering, as well as vortical and swirling motions within particle clouds. Multiresolution analysis is performed by applying a wavelet decomposition to the divergence and curl of the particle velocities. Thus the clustering dynamics across multiple scales can be assessed. Scales at which clustering formation and destruction are most active can hence be identified. In addition, the impact of Stokes numbers and gravity on the divergence, rotational, and swirling motions of particle clouds are analyzed. Our results reveal significant differences in particle behavior due to gravity. These gravitational effects become more pronounced at higher Stokes numbers, resulting in particle motion transitions from relatively erratic to more coherent patterns, thereby providing valuable insights into the interplay between turbulence and gravitational effects in particle-laden flows.

Ref.:

T. Maurel-Oujia, K. Matsuda and K. Schneider.

Multiscale dynamics of inertial particles in turbulence with and without the effect of gravitational settling.

Preprint, 04/2025.