Abstract
Suspended sediment in open-channel flows has been paid great attention in river engineering. It has been pointed out that flow resistance is changed by the existence of sand particles. Moreover, knowledge of interaction between sand-particles (solid-phase) and water (fluid-phase) is necessary to improve sediment transport rate formula. However, the mechanism of particle-fluid interactions is not fully understood. In this study, simultaneous measurements were conducted with discriminator PTV in rough open-channel flows with suspended sediment. The roughness elements were set up on the channel-bed. Consequently, the relative velocity between particles and fluid and the turbulence modulation were investigated by changing the particle concentration systematically.