Modification of near-wall coherent structures by inertial particles

Turbulent planar Couette flow is simulated at a constant dispersed phase mass loading of ϕ m = 0.25 for particle Stokes numbers of St K = [O(1), O(10), O(100)] (based on the Stokes time scale of the particle and the Kolmogorov time scale of the flow) and bulk Reynolds numbers of Re b = [8100, 24000, 72000] (based on the plate velocity difference and separation distance).

Statistics of swirling strength \λ ci \ are used to evaluate the impact of particles on near-wall motions which are responsible for turbulent, wall-normal momentum transport. Instantaneously, the number of high-strength swirling motions near the wall decreases significantly in the presence of particles, and this trend is enhanced with increasing Re b . Conditional averages are computed using linear stochastic estimation, providing the average structures responsible for ejection events near the wall.