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Benchmarking 3D CFD for Studies on Turbulent Flow Around Fish-Shaped Bodies

Author(s): Ali Hassan Khan; Karla Ruiz Hussmann; Dennis Powalla; Stefan Hoerner; Maarja Kruusmaa; Jeffrey A. Tuhtan

Linked Author(s): Jeffrey Tuhtan, Stefan Hoerner

Keywords: Fish habitat; Turbulence models; Boundary layer

Abstract: Fish use their lateral line flow sensing system to locate food, avoid predators and to navigate in turbulent, dark and turbid waters. Biophysical studies of the lateral line indicate that fish are capable of sensing pressure, velocity, and acceleration of the near-body flow field, as well as their gradients at rates between 20 and 400 Hz. This allows fish to perceive minute changes in the hydrodynamic environment, referred to as “touch at a distance”. Previous investigations on near-body flows around fish have illustrated that basic fish-flow interactions can be evaluated using computational fluid dynamics (CFD). Despite these promising findings, there remains a gap in applying CFD to lateral line studies, largely because it is not known which turbulence models are suitable to simulate flows around fish-shaped bodies. To address this, RANS turbulence models are used to simulate a benchmark turbulent flow (Re=6.8x105) around the body of a 3D printed brown trout in an open channel flume. Three different RANS models, the standard k- ϵ, k-ω SST, and Spalart Allmaras were selected based on their applicability. The RANS model assessment was validated in a 1:1 physical open channel flume from laser doppler anemometer (LDA) measurements taken at 250 points distributed around the fish-shaped body, as near as 3 mm from the surface. Furthermore, the effects of modelled and resolved boundary layers were also evaluated. The results of this open source and open data benchmark study provide a numerical model can be used by others for further CFD research on fish flow interactions in fishways, rivers and possibly even to study turbine passage.


Year: 2022

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