Numerical simulation of diameter-to-depth ratio on hydrodynamics in four tank structures

The hydrodynamic performance of aquaculture tanks is crucial for fish welfare and tank self-cleaning. To optimize tank geometry and improve the flow environment, this study employed computational fluid dynamics to investigate the effects of varying diameter-to-depth ratios (L/H) on four tank types: circular, square arc angle, octagonal, and square. The hydrodynamic performance was assessed by analyzing flow velocity, vortex generation, turbulence kinetic energy, turbulence dissipation rate, and effective energy utilization. The numerical model was validated through physical experiments. Results indicated that increasing the diameter-to-depth ratio within the same tank type led to a progressive decrease in turbulence intensity, an expansion of low-velocity areas, and a reduction in average velocity and energy utilization coefficient. Optimal diameter-to-depth ratios ranged from 2:1 to 5:1 for circular, square arc angle, and octagonal tanks, and 2:1 to 3:1 for square tanks. Tanks within these optimal ranges exhibited superior hydrodynamic performance. Overall, this study provides a theoretical basis for selecting aquaculture tanks with optimal diameter-to-depth ratios.