Numerical Analysis on the Effect of Slot Width on the Design of Vertical Slot Fishways

An accurately designed fishway plays an important role in dimensioning migration issues of fish and assists in allowing fish to meet their life cycle's essential necessities. ANSYS FLUENT was used to study the effect of changing slot width on the velocity, turbulence kinetic energy, and head difference (Δh) in water level inside the fishway. The turbulence model was used to predict the local zone turbulence inside the fishway. Using a previously designed model suggested by Zhang in 2017, this study investigated the influence of the change of the slot width for five values, 0.2, 0.25,0.3,0.4, and 0.5 m. The velocity value obtained for 0.2 m slot width (bo), which represented 10% from pool width (B), was 1.57 m/s. While, for a slot width of 0.5 m which represented 25% from pool width, the velocity value was 1.59 m/s with high turbulence regions inside the pools due to the increase in the velocity of the flow. The best flow velocity obtained was 1.23 m/s. This value was obtained when using a 0.3 m value for the slot width. The turbulence kinetic energy for this value of the slot width was 0.08 m^2;/s^2;. Therefore, the value of 0.3 m of the slot width was considered as the optimum value for the examined vertical slot fishway design. The optimum ratio of the slot width to the pool width (b_o/B) was 15%.