Numerical Simulation Study On Flows In Natural-like Fishway Of Low-head Junction

Based on a certain low-head ecological weir project's requirement of the fishway construction and fish migration, a three-dimensional mathematical model of a natural fishway was established. The structure of the fishway which includes the bottom slope and the number of partition walls has great influence on the water flow conditions of the fishway pond room, which were analyzed from three aspects: the flow pattern of the tank room, the mainstream flow velocity, and the turbulent kinetic energy. The numerical simulation results were verified by model tests. The results of the research show that when the bottom slope is set to i = 1:35 the natural fishway has an obvious three-dimensional water flow structure. What's more, under this circumstance, the mainstream of the fishway is clear, the flow pattern is good. The overall turbulent kinetic energy is not large, and the maximum flow velocity at the vertical joint is basically the same, slower than 1.5ms−1, which basically meets the target fish's traceability requirements. With pebbles applied, the flow of the water in the pond room becomes richer. With the traceback path increased, the efficiency of fish communities can be vastly improved. The actual application of the fishway should adjust to the design of the ecological weir and its topographic and geological conditions.