Behavior of particles in turbulence over a wavy boundary

Understanding the mechanism controlling the particle motion in flow over a complex boundary is of great importance for many engineering fields. It is well known that fluid flowing over a wavy boundary creates turbulence that is remarkably different from the flow over a flat wall. Previous studies have presented the role of vortical structures over a wavy boundary, which is associated with particle clustering near the boundary. In this study, behavior of particles in turbulence over a wavy wall is investigated by direct numerical simulation of a turbulent wavy channel flow with laden particles. Our investigation shows that particles interact selectively with vortical structures and accumulate in a specific region along the wavy wall. Active deposition and resuspension occur in the upslope region where streamwise vortices are concentrated. Depending on the particle Stokes number and waviness of the wall, a strip or streak pattern of particle clustering near the wall is observed due to the combined effect of the wavy wall and vortical structures. However, due to the particle inertia, particle velocity and its fluctuation do not change as much as fluid velocity along the wavy boundary. Statistics and relevant physical interpretations of particle motion are presented.