Numerical study on the performance of circular juvenile fish breeding ponds

Abstract

Due to the recent tendency to use circular ponds of closed-circuit systems in the fish farming industry, it seems necessary to investigate the flow pattern performance for improving water hydrodynamic behavior considering the input conditions. Although pond inflow conditions play a major role in the formation of rotational flow, in most cases, these ponds cannot be optimally used due to a lack of appropriate solutions. Therefore, this study presents the computational fluid dynamics model of a circular fish farming pond with a volume of 1.57 m3 based on incompressible steady Reynolds averaged Navier-Stokes formation using a realizable K-ε viscous model. Numerical modeling of the angle change of pond inflow is put on the agenda at three levels, and the inflow momentum force is considered at four levels to investigate vortex formation and its effect on the efficiency of ponds. The results indicate TKE is directly correlated with the inflow momentum force. In the case of injecting the flow tangentially to the pond wall, the maximum TKE is observed in the areas tangential to the pond wall. The formed vortices are analyzed using two vortex quantification methods of vortex strength and normalized velocity. The results demonstrate the maximum vortex strength is at 20–40% of the water level when injecting the flow tangentially into the pond wall (α3 = 30°). The model results suggest installing inlet nozzles tangentially to the pond wall and adjusting inflow with the minimum momentum force to improve rotational flow hydrodynamic performance.