Effects of surface roughness on overflow discharge of embankment weirs  

作　　者：Shang-tuo Qian Yan Zhang Hui Xu Xiao-sheng Wang Jian-gang Feng Zhi-xiang Li 

机构地区：[1]College of Agricultural Science and Engineering,Hohai University,Nanjing,210098,China [2]College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing,210098,China [3]Power China Huadong Engineering Corporation Limited,Hangzhou,311122,China

出　　处：《Journal of Hydrodynamics》2021年第4期773-781,共9页水动力学研究与进展B辑（英文版）

基　　金：Project supported by the National Natural Science Foundation of China (Grant Nos.51809079, 51809081);the Fundamental Research Funds for the Central Universities (Grant No.2019B18414).

摘　　要：A numerical study was performed on the embankment weir overflows with various surface roughness and tailwater submergence, to better understand the effects of weir roughness on discharge performances under the free and submerged conditions. The variation of flow regime is captured, from the free overflow, submerged hydraulic jump, to surface flow with increasing tailwater depth. A roughness factor is introduced to reflect the reduction in discharge caused by weir roughness. The roughness factor decreases with the roughness height, and it also depends on the tailwater depth, highlighting various relations of the roughness factor with the roughness height between different flow regimes, which is linear for the free overflow and submerged hydraulic jump while exponential for the surface flow. Accordingly, the effects of weir roughness on overflow discharge appear nonnegligible for the significant roughness height and the surface flow regime occurring under considerable tailwater submergence. The established empirical expressions of discharge coefficient and submergence and roughness factors make it possible to predict the discharge over embankment weirs considering both tailwater submergence and surface roughness.

关 键 词：DISCHARGE embankment weir numerical simulation tailwater submergence surface roughness 

分 类 号：O35[理学—流体力学]