Flow pattern upstream of a constriction in an erodible channel

In the present paper flow pattern at a constriction in an open channel is studied experimentally. A constriction as a model of bridge site is constructed in a flume 73.5 cm wide and with erodible bed. Measurements were carried out after the scour hole was reached to its equilibrium condition. Tests were conducted with one flow discharge and two tail waters. Flow velocity was measured in 3 directions simultaneously with an ADV. Based on instantaneous velocities, turbulence intensity was also calculated and analyzed. The effect of constriction on flow pattern was then studied based on velocity and turbulence measurements in x, y and z directions.