Comparing the Discharge Coefficients of Labyrinth Weir Featuring Different Geometries and Laboratory Model Using Flow-3D Software

One effective method of increasing the length of the weir for a given weir width is the use of weirs featuring nonlinear plans, namely triangular, trapezoidal and parabolic, that are generally termed labyrinth or zigzag weirs. These are made in one and/or several cycles and as a consequence to the construction of these weirs, the volume of flow passing through them increases and lower free height of the current will be needed in the upstream section in respect to the linear weirs. The issue becomes more important when the weir is served to discharge the floodwater and leads to the facilitation of the flow of the flood current. The present study investigated 4 discharge rates (5l/s, 10 l/s, 15 l/s and 20 l/s) for a channel width and height of, respectively, 30cm and 40cm in trapezoidal, square, triangular and piano key labyrinth weirs in laboratory using Flow 3D software which was in diffusion model K-ε in type RNG was investigated and the results were compared. From among all the models, triangular labyrinth weir accounted for the highest discharge coefficient. It was found out that the Ht/P ratio increases for all of the models results in the decrease in the discharge coefficient. However, it can be concluded that there is a relatively good match between the numerically acquired and laboratory values.The best range for proportion Ht/P for design is between 0.14-0.42 that the maximum discharge coefficient equivalent to Cd=1.24 would be placed in this range.