In order to solve the upstream demand of small fish with weak swimming ability in the vertical slot fishway, an anti-flow cylinder is added to the migration channel between the long and short baffles. Hydro 3D open source code and LES-based numerical simulation technology are used to simulate the flow field in the vertical slot fishway before and after the anti-flow cylinder is added. According to the streamline distribution in the time-averaged flow field, the results show that the area of the vortex area in the pool is reduced after adding the blocking cylinder, which solves the problem of lack of sense of direction in the process of fish upstream in the traditional vertical slot fishway. The turbulent kinetic energy in the pool increases by 20%, which raised the energy dissipation of the water flow and reduced the energy consumption during the fish upstream process. The increase of vorticity around the long and short baffles and the blocking cylinder may have an adverse effect on the stability of the fish during swimming. However, according to the vortex structure, the vortex diameter behind the blocking cylinder is less than 76% of the body length of the small fish, so it has little impact on the stability of the fish during swimming. In summary, the setting of a flow blocking cylinder in the vertical slit fishway can improve the success rate of small fish upstream.

vertical slit fishway  /  obstructive flow cylinder  /  turbulence  /  large eddy simulation  /  hydraulic characteristics