An Examination of Rectangular Side Weir Discharge Coefficient Equations under Subcritical Condition

摘要

Side weir is a popular hydraulic structure used widely in drainage and irrigation systems and wastewater treatment plants. This paper probes some well-known discharge coefficient equations to assess the condition of validation and accuracy for each. In order to achieve this goal, 193 tests were run. 15 well-known equations presented in table 1 were meticulously investigated to examine their accuracy. Despite DeMarchi's assumptions, the results reveal that specific energy is not constant along lateral weir and ignoring its gradient along lateral weir is not reasonable. Further investigation renders gradient of specific energy greater than water profile gradient along this weir in some cases; therefore this paper presents a discharge coefficient equation appropriate for mentioned condition.