HYDRODYNAMIC EFFECTS OF STRIP ROUGHNESS ON SURFACE VELOCITY DIVERGENCE IN OPEN-CHANNEL TURBULENT FLOWS

Abstract

 We focused on hydrodynamic effects of the strip roughness on the surface-velocity divergence value to breakthrough about physical modeling of gas transfer mechanism in natural rivers. Accurate PIV measurements were conducted in a computer-controlled laboratory flume varying water discharge and roughness spacing, systematically, in order to obtain the space and time distributions of surface velocity divergence, turbulent kinetic energy and dissipation rate. Finally, a new practical model to predict the surface velocity divergence could be proposed successfully considering turbulence micro scales.