Local Scour on Noncohesive Beds by a Submerged Horizontal Circular Wall Jet

Abstract

Local scour on noncohesive beds caused by horizontal circular wall jets in submerged environments is investigated in this study. The effects of the ratios of sediment size-to-hydraulic radius, Ks=d50/Rh, on the jet scour are considered. A total of 420 datasets of previous observations are compiled and 12 laboratory experiments in the Ks range of 0.44–2.44 are conducted to investigate the effect of Ks on scour dimensions. A dimensional analysis shows that both the particle gravity and bed resistance to the flow play important roles in the scour. Analysis on the data shows that the maximum scour dimensions vary linearly with the densimetric Froude number F84 and nonmonotonically with a manner of a Gaussian function of Ks, respectively. Finally, the formulas to predict the maximum scour dimensions of a submerged horizontal circular wall jet are proposed, which are fairly well in line with existing laboratory and field data.