Numerical analysis of labyrinth weir height on discharge coefficient

This study investigated the performance of a labyrinth weir with a trapezoidal cross-section at different heights. For this purpose, the geometry of the weirs was designed in Inventor software, and simulation was performed in Flow3D software. Validated the model with laboratory data, and the results of the model were in good agreement with the results of laboratory data. Examined the numerical model at three heights of 10, 14 and 18 cm and three different angles and two apex widths; Analysis of the results showed that with decreasing the weir height (P), the discharge coefficient (Cd) increases. Reducing the weir height by 44% increased the average discharge coefficient by 2 to 3%. In all simulated models, with decreasing relative water head, the decreasing trend of discharge coefficient was also reduced. During the constant crest length, with a 100% increase in the weir angle, the discharge coefficient of all three weir heights increased by 20 to 25%. A 40% increase in crest length at a fixed angle increased the average discharge coefficients of all three heights by 12 to 15%. As a result, at a constant angle, the increase in crest length is greater than the second case (constant crest length and increase in weir angle) on the flow rate; This is important in designing labyrinth weirs to have a maximum discharge coefficient and should be considered.