Modulation of large-scale structures by neutrally buoyant and inertial finite-size particles in turbulent Couette flow

Particle-resolved numerical simulations based on the Force Coupling Method are carried out to study the effect of finite-size particles on turbulent plane Couette flow. The Reynolds number is close to the laminar-turbulent transition, such that large-scale rotational structures are well developed and self-sustained. The study particularly considers the effect of concentration, particle size, and particle-to-fluid density ratio on the mixture flow features. Time-averaged profiles, in the wall-normal direction, of the mean flow and Reynolds stress components reveal that there is no significant difference between single-phase and two-phase flows at equivalent effective Reynolds number, except that the wall shear stress is higher for the two-phase flow. However, temporal and modal analysis of flow fluctuations suggest that besides injecting small-scale perturbation due to their rigidity, particles have an effect on the regeneration cycle of turbulence. Indeed, the shape of the streaks and the intermittent character of the flow (amplitude and period of oscillation of the modal fluctuation energy) are all altered by the particle presence, and especially by the inertial ones.