The effects of laboratory canal size and cylindrical weir-gate diameter on discharge coefficient

Inthis study, the effects of canal size on discharge coefficient of cylindrical weir-gate were investigated, using two flumes (6 ×0.075×0.175 and 10×0.6×0.7 meter dimension). The results show that the discharge coefficient will rise on small canals due to increasing both the parameters (the ratio of upstream water depth to the gate opening and the upstream water depth to structure diameter) but decreases initially then rises on large canals. The range of discharge coefficient on small and large canals variesfrom 0.55 to 0.9 and 0.75 to 1.05 subsequently. At the end, an equation is presented in order to estimate discharge for each canal.