Detailed measurements on particle-turbulence interaction within the suspension layer of a symmetric oscillatory sheet flow

The particle-resolved coupled dynamics between sediment particles and turbulence under sheet flow conditions remains an open problem due to the prohibitive computational expense in direct simulation and harsh imaging environment in experimental measurements. Enabled by the recently developed apertured filter method, a whole field, phase-locked time-resolved, particle-resolved and concurrent measurement of both the fluid and the sediment phase was conducted within the suspension layer up to a concentration of C = 1% in a symmetric oscillatory sheet flow (period T = 5s, free stream velocity U_o = 1m/s, sediment mean diameter d = 240μm). At every 10^○, the instantaneous sediment particle 3D locations within a well-defined measurement volume (around 1mm thick) were reconstructed and their temporal trajectories were computed; on the same measurement plane, carrier phase flow velocities (2D3C) were calculated by stereoscopic particle image velocimetry with a resolution of 1.6mm. Analysis will be focused upon the coupled dynamics between phases manifested at different phase angles. The evolution of slip velocity profiles, preferential concentrations, and modulated turbulent statistics are presented, providing explanations for the resultant sediment concentration profiles.