Flow resistance in large-scale roughness condition

This paper presents an experimental investigation of the flow resistance in long chutes with a slope of up to 9% and large-scale roughness. Rock chutes generally have steep slopes and the presence of large rocks induces great resistance to the flow. The chute bed was characterized by different sizes of crushed stones with protruding boulders. The proposed relationship correlates the flow resistance in terms of the Darcy–Weisbach friction factor with and without protruding boulders. The proposed logarithmic law is a function of the relative submergence, the slope, and the boulder concentration. A comparison of the data calculated using the proposed logarithmic law with those from earlier experiments shows a reasonable agreement in the tested experimental range.