Location: Cool and Cold Water Aquaculture ResearchTitle: Influence of inlet and outlet placement on the hydrodynamics of culture tanks for Atlantic salmon
|GORLE, JAGAN - Nofima
|TERJESEN, BENKIK - Nofima
|SUMMERFELT, STEVEN - Freshwater Institute
Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/13/2020
Publication Date: 7/15/2020
Citation: Gorle, J.M., Terjesen, B.F., Summerfelt, S.T. 2020. Influence of inlet and outlet placement on the hydrodynamics of culture tanks for Atlantic salmon. International Journal of Molecular Sciences. 188:105944. https://doi.org/10.1016/j.ijmecsci.2020.105944.
Interpretive Summary: Optimizing water movement in very large circular salmon tanks (~1,000 m3) on fish farms can be challenging. To address this challenge, four combinations of tank water inlet and outlet designs were evaluated at a commercial aquaculture site using computational fluid dynamics, with the dispersion of biosolids within the study tank being assessed using uniformly sized and tracked particles in the water column. The effects of inlet and outlet placement within the tank on water velocity, vorticity and turbulence were assessed. It was determined that water flow dynamics could be improved using the bottom-drain and corner-inlet options, which strengthens rotational flow with better uniformity. These improvements could provide better particle removal and therefore improve tank self-cleaning.
Technical Abstract: The salmon farming industry has recently shifted to larger culture tanks with greater water flows to optimize the land-based production, but tanks approaching 1000 m3 in volume create challenging hydrodynamics. This paper presents a computational study of four combinations of inlet and outlet designs of a commercial land- based aquaculture tank. Windows-based OpenFOAM solvers are used to solve the conservation equations for tank hydrodynamics with an implicit unsteady second-order Eulerian (finite volume) technique on unstructured hybrid meshes. The model is validated by the velocity measurements at discrete locations in the tank using acoustic doppler velocimetry. To understand the dispersion of biosolids in the tank, 500 particles with a uniform size of 200 µm are tracked in the Lagrangian frame. While the tank’s Reynolds number varies between 2E6 - 3.5E6 depending on the flow exchange rate, the local Reynolds number at the inlet pipe is about 2E5 which discovers the drag-crisis phenomenon. The effect of inlet and outlet placement on the velocity, vorticity and turbulence is addressed. The existing tank design could be improved using the bottom-drain and corner-inlet options, which strengthens rotational flow with better uniformity. Such design change is also proved to provide better particle removal and thus ensure the improved self-cleaning ability of the tank.