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Abstract

The study aims to investigate the effect of fish movement on the flow field in the aquaculture tank of a recirculating water aquaculture system. Herein, based on the Navier-Stokes equations and the RNG k-ε turbulence model, the flow field in the aquaculture tank with fish movement was numerically simulated using the multiple reference frame (MRF) model and compared with the numerical simulation results of the fishless aquaculture tank. The results revealed that the overall mean flow velocity in the tank decreased significantly when the fish swam counter-currently with a fixed trajectory, and the overall mean flow velocity increased slightly when the number of fish increased. When the same number of fish swam counter-currently with a fixed trajectory, the effect of side-by-side distribution on the overall mean flow velocity in the tank was slightly greater than that of the back-and-forth and top-and-bottom distributions. Under the influence of fish counter-current swimming, the flow field uniformity in the aquaculture tank was significantly reduced, the turbulence intensity increased, the flow velocity at the tank wall increased, and the low-flow velocity area appeared in the center of the tank. The study demonstrated the necessity of considering the impact of fish counter-current swimming on the flow field within an aquaculture tank. This consideration is crucial when seeking to raise fish welfare, improve production operation management and optimize the structure of the aquaculture tank.

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