Effect of parameters of pool geometry on flow characteristics in low slope vertical slot fishways

Abstract

A 3D numerical model using the re-normalized group (RNG) k-ϵ turbulent closure was applied to study the hydraulic characteristics of a fishway and their dependence on the shape of the baffles, bed slope and water level difference between two adjacent pools. The results show the hydraulic conditions of a fishway with Type H baffles are better than that of a fishway with Type L baffles based on the analysis of turbulent kinetic energy, energy dissipation rate and vorticity. The flow velocity, turbulent kinetic energy and average energy dissipation rates per unit volume are all positively correlated with bed slopes. Water level difference between two adjacent pools is the main influencing factor for the velocity in the vertical slot. When the water level differences between two adjacent pools are the same, the flow velocities in the vertical slot are almost equal even if the fishways have totally different slopes. These findings enable the design of economic fishways with steep slopes but slower water flow.