Effect of flow rate and dissolved oxygen distribution on aeration of the recirculating aquaculture tank

Abstract

In this study, Reynolds-Averaged Navier-Stokes computational fluid dynamics method was employed to study the flow rate and dissolved oxygen distribution characteristics during aeration in aquaculture tanks. The gas–liquid mass transfer model was used to simulate oxygen transfer between microbubbles and seawater. Finite element models of the full-scale aquaculture tank and fish were established. The mesh sensitivity was verified. The impact of different aeration pipe layouts on flow fields and dissolved oxygen distribution was systematically analyzed. Results showed that a 6 × 8 aeration pipe layout was optimal, producing distinct vortex flows that enhanced water mixing and dissolved oxygen uniformity. The numerical model was validated with a Mean Relative Error (MRE) of 6.89 % and R² = 0.96. Under pure oxygen aeration (>99.99 %), seawater (30 ‰ salinity, 20℃) reached a saturated dissolved oxygen concentration of 39.40 mg/L. In the event of oxygen cone failure, the aeration oxygen supply must be increased by 10 kg O₂/h beyond fish oxygen consumption to maintain safe conditions. The study also revealed that higher oxygen consumption levels increased dissolved oxygen concentration differences in vertical and horizontal directions. These findings support optimizing aeration design and oxygen management in aquaculture systems.