Numerical Investigation of Geometric Parameters Effect of the Labyrinth Weir on the Discharge Coefficient

Weirs, as overflow structures, are extensively used for the measurement of flow, its diversion and control in the open canals. Labyrinth weir due to more effective length than conventional weirs, allows passing more discharge in narrow canals. Determination the design criteria for the practical application of these weirs need more investigation. Weir angle and its position relative to the flow direction are the most effective parameters on the discharge coefficient. In this study, Fluent software was used as a virtual laboratory and extensive experiments were carried out to investigate the effect of geometry on the labyrinth weir discharge coefficient. The variables were the height of weir, the angle of the weir and the discharge. The discharge coefficients obtained from these experiments were then compared with the corresponding values obtained from the usual rectangular sharp crested weir experiments. Comparison of the results showed that in all cases with different vertex angle, flow discharge coefficients are in a satisfactory range for relative effective head less than 0.3. The discharge coefficient is decreased for relative effective head more than 0.3 due to the collision of water napes. It showed the higher weir, the more discharge capacity. As a result, the labyrinth weirs have a better performance in comparison with the common sharp crested.