Numerical Modeling of the Labyrinth Weirs with Additional Passages Added onto Weir’s Wing Using Flow-3D Software and Comparison to the Laboratory Results

Labyrinth weirs are some cost-effective structures, having trapezoidal, triangular and other formats, utilized for increasing the output efficiency in a limited width. Raising the capacity of labyrinth weirs via increasing their width is not always possible. The labyrinth weirs are used due to the increase in their efficient length on a given hydraulic height and width. The present study investigates the weirs having trapezoidal polyhedron format, on the wings of which some new labyrinth have been added so that their spillover discharge rate will be reinforced. The experiments in this study were conducted on 27 laboratory models having 9 different discharge rates, on whose wings double labyrinth have been added, totally through 243 experiment. Besides the spillover simulations were performed using the Flow-3D software. The results obtained from the numerical analysis for the determining the spillovers discharge rate coefficient were validated using laboratory data and it demonstrated a good correspondence between the numerical solutions and laboratory findings. It is also suggested that the Flow-3D software has a high potential in simulating the flow on labyrinth weirs. Laboratory results also indicated that, regarding all the compound polyhedron trapezoidal weirs, the parameter ratio, flow rate coefficient to ratio (Ht: total hydraulic load and P: spillways height) firstly raise and then start to reduce once they reach the maximum level. The spillover discharge rate increases for a given when the effective length of the weirs’ wing is raised. The discharge rate on the weirs having semi-circular compound format is better than this rate of ones having the square format and the ones having compound square format have spillover discharge rates better than the ones having simple trapezoidal format, in a manner that the discharge rate of the current flow is increased 15 percent more than the trapezoidal dam labyrinth spillways and flow rate coefficient interval increases from 0.4 percent of dam labyrinth spillways to 0.65 on the compound spillways.