Sensitive analyses of flow property to turbulence model in swirls simulation within aquaculture tanks

Abstract

Water swirls in tanks with bottom drain(s), which is observed in aquaculture tanks. Numerical simulation of the swirling field with the general two-equation turbulence models fails to describe the swirling phenomenon and the investigating results are less convincing. This study simulates the swirling flow fields with four categories of turbulence models, they are the laminar model, the turbulent-viscosity model, the Reynolds stress model, and the Large Eddy Simulation model. Results show that the swirling phenomenon is successfully numerically reproduced except for the turbulent-viscosity model. Although the flow properties predicted with the turbulent-viscosity model are different from other turbulence models, the results are meaningful from the perspective of statistical items (mean, standard variation, uniformity, PDF, CFD). For cases with swirls, the flow field can be divided into a forced vortex and a free vortex, and their tangential velocity profiles can be described with a theoretical formula. Considering the numerical cost and the reproduction of experiments, the Reynolds stress turbulence model is preferable in studies of the flow properties of aquaculture tanks.