CFD simulated model and experimental tests for critical depth and flowrate estimation over a broad-crested weir under the longitudinal slope effect

Abstract

This work consists of an experimental approach using rectangular broad-crested weirs having varied edge geometries to investigate the longitudinal slope effect on the relationship between the critical depth and the depth at centre of the weir. Based on this relationship, a statistical regression analysis method was used to derive a new and precise formula to estimate the flowrate over square and rounded broad-crested weirs. In all cases, the depth at the centre of the weir was considered as a control section. In general, it was found that the longitudinal slope So has an insignificant effect on the relationship between the critical depth and the depth at the centre of the weir and the suggested new flowrate estimation formula. Also, computational fluid dynamic model using FLUENT ANSYS version 16 was also designed and operated to simulate the problem based on the VOF method and the standard k~e method. The CFD model provided a very good simulation of the problem for the new flowrate formula and the existing pressure head at the centre of the weir. Comparing the results of the new formula with that of the actual experimental tests and the results of the simulation model indicted a very good agreement.