Abstract: Fishway is an important engineering measure for fish migration. In this paper, 3D turbulence numerical simulation of the flow field in fishway pool was carried out using standard RNG k-ε turbulence model and Tru-VOF tracking free liquid level method based on Flow-3D. The spatial distribution of flow velocity and flow pattern in fishway pool was studied, and the influence of the hydraulic characteristics of fishway on the upstream migration of target fish was analyzed. Results show that in the overflow weir combined with vertical slot fishway at design velocity (v=0.75 m/s), the average flow velocity at slot was 0.83 m/s (ranging between 0.76 m/s and 0.89 m/s), the flow velocity above weir was from 0.90 m/s to 1.12 m/s, and the velocity in backflow zone was in the range of 0.09-0.25 m/s, all within the limits of fish swimming ability. Nevertheless, in the adjacent of the slot baffle, the main stream obviously adhered to the wall. The design of fishway pool was optimized to meet the upstreaming requirements of fish.

Key words: fishway, combination baffle type, numerical simulation, hydraulic characteristics, flow field