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Experimental study on the 3D-flow field of a free-surface vortex using stereo PIV

Author(s): Alex Duinmeijer; Gosse Oldenziel; Francois Clemens

Linked Author(s): Alex Duinmeijer, François Clemens

Keywords: Air core depth; axial vortex flow; Burgers vortex model; experiments; stereo particle image velocimetry (SPIV); vortex dynamics; vortex core radius

Abstract: ABSTRACTIn order to analyse the flow characteristics of free-surface vortexes and to validate the Burgers vortex model by using stereo particle image velocimetry, experiments are conducted in a 600 mm diameter vortex tank. Measured axial velocities indicate that 10–25% of the flow is transported through the vortex core. The velocity profiles show that the axial flow is concentrated in a domain bounded by two times the core radius. Despite Burgers’ assumption of radially independent axial velocity profiles, the model quantifies the tangential velocity profile within a relative uncertainty of circa 10%. The measurements show that it seems valid to use Burgers’ model to obtain an estimate for the core radius by taking the average axial velocity over a radial domain of approximately 2.2 times the core radius. The Burgers model quantifies the air core depth with an uncertainty of 20% relative to the measurements. When compared with the magnitude of vorticity diffusion by molecular viscosity, the experiments show that there is no significant diffusion by radial turbulence.

DOI: https://doi.org/10.1080/00221686.2018.1555558

Year: 2020

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