Numerical investigations on dissolved oxygen field performance of octagonal culture tank based on computational fluid dynamics

In aquaculture, dissolved oxygen (DO) is essential for the growth and development of aquatic products, particularly the recirculating aquaculture system (RAS). Measurement and control of DO concentrations have been extensively researched, but the transport mechanisms have not been realized due to the lack of reliable flow transfer models. To solve this problem, computational fluid dynamics (CFD) coupled with Euler-Euler and Species Transport Model (CFD-Euler-Euler-STM) model was employed to investigate the spatial and temporal variation of DO in recirculating aquaculture tanks. In this study, a user-defined function (UDF) was used to couple the CFD-Euler-Euler-STM. In this study, the CFD-Euler-Euler-STM model can simulate the detailed 3D flow field distribution of DO (MAPE = 4.40 %) by comparing on-site measurement data with simulation results. The results show that the maximum DO concentration is 5.68 mg/L at a gas holdup of 0.098, and that higher relative velocity and flow velocity magnitude lead to higher dissolved oxygen concentrations. In addition, the DO concentration is consistent with the streamline distribution. Moreover, the model provides a promising tool platform for the accurate regulation of DO and aeration optimization in aquaculture.