[1] We explored the dependence of experimental bedrock erosion rate on shear stress, bed load sediment flux, alluvial bed cover, and evolving channel morphology. We isolated these variables experimentally by systematically varying gravel sediment flux Qs and water discharge Qw in a laboratory flume, gradually abrading weak concrete “bedrock.” All else held constant, we found that (1) erosion ra...

We investigate granular transport by a fluid flow under steady-state driving conditions, from the bed-load regime to the suspension regime, with an experimental system based on a conical rheometer. The mean granular volume fraction φg , the mean granular velocity ug , and the fluid velocity uf are obtained as a function of depth inside the bed using refractive index matching and particle-tracki...

In the laboratory we used an idealized rotorwash flow—an axisymmetric jet impinges normally on a packed bed of cohesionless particles—and measured the spatially varying flow field and entrainment flux under an axisymmetric jet over a range of jet exit velocities and bed materials. We found that the erosion of the bed is driven by turbulent surface shear stress, quantified by the turbulent kinet...

The average bed shear stress and bed friction factor of samples with any roughness was derived from the head loss between upstream and downstream of a test section in an erosion tunnel. The method was validated in both hydraulically smooth (plexiglass; Reynolds number less than 25,000) and rough regimes (calibrated particles with known roughness). As a first step toward using this method on nat...

The distribution of the wall shear stress on the bed and sidewalls of an open channel receiving lateral inflow was obtained from experimental measurements of the distribution of the velocity in the viscous sublayer using a laser doppler velocimeter. The experiments were conducted in a 0.4 m wide by 7.5 m long flume. Lateral inflow was provided into the channel from above via sets of nozzles pos...

introduction: bridges are certainly one of the most important structures but costly service elements in a transport system. the bridges are very required to access the damaged areas in emergency situations such as floods and earthquakes. scour around the foundations of bridge piers exposed to the flowing water than can destroy the bridge itself is a subject of major concern. flow pattern is kno...

The effect of shear stress at the endothelium in the attenuation of the noradrenaline-induced constriction of the femoral vascular bed perfused at a constant blood flow was investigated in 16 anesthetized cats. It is known that the adrenergic vasoconstriction of the femoral vascular bed is considerably greater at a constant pressure perfusion than at a constant blood flow. This difference may d...