Prediction of Local Scour Depth Downstream of an Apron Under Wall Jets

Abstract

An experimental analysis on the development of scour hole downstream of a rigid apron under wall jets coming out from the opening of a sluice gate has been performed, and the results have been presented thereof. The similarity in the scour profiles with time has been shown by plotting the scour profile at different times. Equilibrium/asymptotic scour depth is achieved after 6–8 h for fine sediment, whereas time taken to achieve equilibrium depth of scour is lesser for coarser sediments. Equilibrium depth of scour is observed to decrease with increasing sluice opening and sediment size, whereas a rise in densimetric Froude number increases the maximum depth of scour. Effect of tailwater level on equilibrium scour depth is such that initially there is a decrease in the maximum depth of scour with rising tailwater level, but after a critical level of tailwater, the asymptotic depth of scour increases with increase in tailwater level. A new empirical equation is proposed for prediction of scour downstream of a rigid apron under wall jets.