عنوان مقاله [English]
نویسندگان [English]چکیده [English]
While flow over stepped spillway is in nappe regime, with gradual increasing of discharge and before changing flow to skimming, transition regime occurs. Different energy dissipation in each flow regime exists and thus understating of hydraulic conditions in the transition boundary of each regime is essential. The purpose of this research is to determine these boundaries among three regimes, their hydraulic conditions and specially governing hydraulic criteria on transition regime which have not been clarified in previous studies. For this purpose, 18 physical models of stepped spillways were built with slope angles of 15, 25 and 45 degrees. Results showed that transition regime depended on discharge and spillway slope. The boundary defined for the transition regime in this study is near the boundary proposed by other researchers, except with some shifting to the right. Comparison of the defined transition boundary in the present study with data of other researchers revealed greater reliability of the present study.