the effect of slot in reducing scour depth of cylindrical bridge pier using flow3d software

Scouring is one of the most important factors in the destruction of bridge piers. one of the ways to reduce scouring depth is to use a slot in the bridge pier. in this research, the flow 3d model was used to simulate the effect of a slot with the same dimensions in two positions parallel to the bed and close to the water surface. the tests were performed at two relative speeds of 0.87 and 0.92. uniform and non-cohesive bed sediments with a geometric standard deviation of 1.4 and an average diameter of 1 mm were used. the results showed that the slot created in the pier of the bridge weakens the eddies around the pier and is effective in reducing scour depth. the slot close to the surface, on average, about 6%, and the slot parallel to the bed, about 26%, are effective in reducing the maximum scour depth compared to the control pier. also, with the increase of froud number from 0.376 to 0.380, scour depth has increased by 11% on average.