TURBULENT STRUCTURES OVER PERMEABLE FIXED ROUGH BED AND EFFECTS OF MOVING PARTICLES ON THE MAIN FLOW

Abstract

 Gravel bed rivers are formed by large particles as gravels and cobbles, and other large particles move on the gravel bed. Therefore, mechanism of interactions between flow and moving large particles should be evaluated. A three dimensional numerical experiment about turbulent flow including rolling and saltating spheres over permeable fixed rough bed was conducted. Turbulent structures of permeable rough bed and effects of moving spheres on the main flow were examined. It is proved that slow flow of low positions is transported to higher positions with saltating particles, then longitudinal velocity of high positions considerably becomes small. So saltating particles have an influence such as the ejection for the main flow. In this condition, turbulence intensities of flows including moving particles become larger than those of clear flow.