An experimental investigation of erosion of a uniform sand bed by a vertical submerged jet shows that the momentum flux of the jet and the distance between nozzle and sediment determines the rate of scour. Under fully turbulent conditions, the relative dimensions of the scour hole depend only upon the time parameter and the ratio between the fictitious axial jet velocity at the bed and the fall velocity of the sediment particles. There exist two distinct values of this ratio, at which the eroding action of the jet becomes particularly effective. At the same mean volume flux, the erosion rate can be more than doubled by pulsations of the jet velocity. For the relative distance between nozzle and bed investigated, the continuous jet has the least erosion capacity as compared to pulsating jets.
