Numerical analysis of thermal and hydrodynamic characteristics in aquaculture tanks with different tank structures

Improving hydrodynamic performance by changing the geometries of aquaculture tanks can facilitate salmon growth. Thus, this study proposed to redesign the aquaculture tank by varying the tank shape, numbers of inlets, and nozzle angles. The hydrodynamic and thermal characteristics of an aquaculture tank were numerically investigated via computational fluid dynamics simulations. The results indicated that the circular tanks mixed better than the octagonal tanks. Secondary vortices were more extensive in a two-inlet than a one-inlet tank. The vortex column in a two-inlet tank was smaller than that in the one-inlet tank. Therefore, the mixing performance of the two-inlet tank was better than that of the one-inlet tank. Further, the flow uniformity could be improved by optimizing the nozzle angle. Consequently, the mixing performance of the radial nozzle tank was better than that of the tangential nozzle tank because the secondary vortices were prominent and vortex column was smaller. A comparison of all the cases revealed the flow uniformity of the radial nozzle case was the highest. The volume percentages corresponding to the suitable velocity for salmon growth and velocity uniformity were 52.27% and 0.878, respectively. Furthermore, the vortex size was reduced and the velocity uniformity was increased by 2.23% by changing the nozzle angle to a radial angle. Therefore, changing the nozzle angle along the radial direction better improved the hydrodynamic characteristics.