Numerical simulation of the pier geometry effects on forming the transverse wave in converged spillways

Investigating the effect of the geometrical characteristics of the piers, i.e. increase in the length of the pier end, could reduce the transverse wave height and help to achieve the optimal design for the converging chute walls height and reducing the construction costs. In this paper, FLOW-3D is used for three-dimensional simulations of the Khair-Abad dam spillway and investigating the spillway piers geometry effects on forming the transverse waves. The simulation results show that the heights of the second and third waves increase by increasing the length of the pier end which is located adjacent to the chute walls due to the superiority of the effect of the chute convergence on the piers end length changes. It is shown that the suitable way to reduce the transverse wave height is increasing the length of the middle pier end. The simulation results demonstrated that the third wave height does not significantly change by increasing the length of the middle pier end more than a specific value and increasing the end length to more than this value to just increases the construction costs. Consequently, a specific length could be recommended for the spillway piers end optimum length to reduce the possibility of generation of the second and third waves and also to reduce the chute walls height.