Accelerations and Mean Trajectories in Turbulent Channel Flow

Abstract

The author shows that even in steady uniform turbulent channel flow there exist on the average mean accelerations and forces acting on fluid particles. These are computed from the flow equations and Laufer’s data. There exist both normal and axial mean accelerations, the latter highly negative (15g and more) in the dissipative “transition” layer near the wall, elsewhere constant. There most river bed-load and dune sand movement occurs. Mixing and sediment transportation are explained dynamically. Mean shear is shown to exist mainly in the dissipative layer. Mean turbulent trajectories are defined.