Numerical modelling of fluid flows in a recirculating aquaculture system

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A new, innovative, recirculating aquaculture system (RAS) has been developed by the Myera Group that wants to be a leader in food security solutions for remote regions. The RAS is based on a modular tank design that provides for targeted feeding, medication, and environmental control in the raising of fish stocks. The novel design uses an airlift pumping mechanism to control water velocity for optimising fish health through exercise, while simultaneously promoting gas exchange and removal of waste.The fluid flow in the airlift pump involves a very complicated combination of two-phase (gas-liquid) bubbly flow with mass exchange. The parameters that interact to change the fluid velocity and air exchange are the mass flow rate of air, the bubble size, the air lift duct geometry, and the piping connections to the modular tank. Predicting how changing any of these parameters will affect the performance of the system is very challenging, yet is essential to improve the design of the system.The main aspect of this proposed work is to develop a detailed numerical model of the three-dimensional two-phase fluid flow in the airlift pump of the RAS. This model will use state-of-the-art computational fluid dynamics (CFD) software and validate against experimental data. The resulting model will predict the fluid flow and mass transfer and be responsive to changes in the geometry and operating conditions. The company will be able to use the model for virtual prototyping of design changes. This will save time and money in moving toward improved designs that are needed for full scale production.