Numerical modelling of flows in vertical single-slot and double-slot fishways

Most of the earlier studies on fishways have been focused on the flow structure by means of hydraulic models. Since the flow structure in a fishway is complicated with free surface and sub- and super-critical flow conditions usually coexist, only a few papers have been published which had applied numerical methods to the flow in fishways. This paper deals with applications of a second order accurate Godunov-type numerical model of the two-dimensional shallow water equations discretized using finite volumes to the flow in vertical slot fishways. Roe's approximate Riemann solver is used for the convection terms to calculate the flux through computational cell edge, and a slope limiter is applied to prevent non-physical oscillations. The model is based on hierarchical quadtree grids automatically generated to fit the boundary configuration. The flows in three types (two types for single-slot and one for double-slot) of vertical slot fishway are simulated and discussed.