Numerical estimation of critical local energy dissipation rate for particle detachment from a bubble-particle aggregate captured within a confined vortex

[Display omitted] •Interaction of a bubble-particle aggregate with a confined vortex investigated.•An interface resolved 3D CFD model developed to quantify the interaction dynamics.•Highspeed shadowgraphy and PIV experiments performed to validate the CFD model.•Correlation of vorticity and local ene...

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Bibliographic Details
Published in:	Minerals engineering 2022-04, Vol.180, p.107508, Article 107508
Main Authors:	Hoque, Mohammad Mainul, Doroodchi, E., Jameson, G.J., Evans, G.M., Mitra, Subhasish
Format:	Article
Language:	eng
Subjects:	Bubble-particle interaction CFD modelling Local energy dissipation rate Particle attachment/detachment Turbulence Vortex
Online Access:	Get full text
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Summary:	[Display omitted] •Interaction of a bubble-particle aggregate with a confined vortex investigated.•An interface resolved 3D CFD model developed to quantify the interaction dynamics.•Highspeed shadowgraphy and PIV experiments performed to validate the CFD model.•Correlation of vorticity and local energy dissipation rate (ε) determined from CFD model.•A force-balance model used to predict particle detachment using ε. In flotation, interactions of bubble-particle aggregates with turbulent flow structures in the liquid medium result in particle detachment. This study aims to simulate this phenomenon involving a bubble-particle aggregate (bubble diameter ∼ 3 mm and particle diameter ∼ 314 µm) interacting with a turbulent flow structure manifested as a confined vortex in a square cavity connected to a square cross-section channel. An interface resolved three dimensional (3D) computational fluid dynamics (CFD) model was developed to quantify the bubble-vortex interaction dynamics over a range of channel Reynolds numbers. The CFD model produced a good agreement with the experimentally measured vorticity magnitude, local energy dissipation rate, and bubble motion. It was shown that a bubble-particle aggregate could be captured within the vortex by suitably varying the channel Reynolds number, eventually leading to particle detachment. A separate force balance analysis was performed to determine a criterion for particle detachment utilising the CFD model predicted vorticity and local energy dissipation rate. It was shown that a critical local energy dissipation rate ∼ 1.59 m2/s3 was required for particle detachment to occur, which was also verified experimentally.
ISSN:	0892-6875 1872-9444