Climate change has made net-pen aquaculture more vulnerable to temperature and water quality fluctuations, limiting feeding and reducing yields. Upwelling systems offer a potential solution; however, current designs are energy-intensive, and their suboptimal fluid dynamics reduce their effectiveness in disrupting thermal stratification and improving water quality. This project proposes an engineered upwelling solution using airlift pumps that require only 10% of the energy used by traditional systems. The goal is to enhance water circulation and cool the upper water layers in net-pen cages. The system is optimized through Computational Fluid Dynamics (CFD) analysis using ANSYS Fluent to simulate both heat and mass transfer within an open net-pen environment. In the CFD model, six 8” FloMov™ pumps are positioned around the circumference of the cage, with suction pipes extending below the thermocline to draw cooler water from deeper layers and circulate it to the surface. Figure 1a shows the temperature distribution on a vertical slice of the net pen, while Figure 1b illustrates the velocity vectors. After 1.5 hours of transient simulation, enhanced mixing was found to provide effective cooling in the upper water regions. Figure 2 displays surface temperatures at various locations, indicating a 2.7°C reduction after 1.5 hours. The next phase of this project will involve field testing the proposed system in an Ontario net-pen facility raising rainbow trout. This will help validate the design and assess its broader applicability across different cage sizes and operational conditions.
Acknowledgement: The authors gratefully acknowledge the Ontario Ministry of Agriculture, Food and Agribusiness (OMAFA) for funding this research under the Ontario Agri-Food Innovation Alliance Tier I grant No. 100108. The support from FloNergia Systems Inc. for supplying the FloMovTM technology and Wahba Engineers for assisting in the CFD analysis is appreciated.