- Title
- Behaviour of coarse particles attached to a bubble within a rotating liquid flow field inside a confined cavity
- Creator
- Hoque, M. M.; Mitra, S.; Moreno-Atanasio, R.; Doroodchi, E.; Evans, G. M.; Jameson, G. J.
- Relation
- IMPC 2020: XXX International Mineral Processing Congress. Proceecings of the XXX International Mineral Processing Congress (IMPC 2020) (Cape Town, South Africa 18-22 October, 2020) p. 1-10
- Relation
- ARC. DP180103971 http://purl.org/au-research/grants/arc/DP180103971
- Publisher
- The South Africans Institute for Mining and Metallurgy
- Resource Type
- conference paper
- Date
- 2020
- Description
- In this study, the detachment behavior of 314 μm diameter silica particles from a single 3 mm diameter bubble rotating in a confined cavity connected to a cross-flowing water channel was investigated. The liquid cross-flow generated a rotating flow inside the confined cavity, which was quantified using 2D particle image velocimetry (PIV) measurements. The fluctuating (x-y) velocity components inside the cavity for each cross-flow velocity, U, were then used to estimate the corresponding time/volume average turbulence intensity values, Ti. Turbulence intensity ranged from 9.3-16.2%. In the absence of a bubble, the rotating vortex within the cavity created a pressure field which decreased towards the center of the vortex; wherein the lowest pressure zone was located at the center of the cavity. The vorticity into the cavity was found to increase with increasing the turbulence intensity. A bubble, both without- and with-particles attached, was introduced into the cavity under different flow conditions and its motion was tracked using the shadowgraphy technique. Experimentally, it was found that the bubble-particle aggregate was trapped at the center of the cavity (low-pressure region) following a spiral trajectory. An interface resolved 3D computational fluid dynamics (CFD) model was developed to predict the particle detachment conditions within the confined cavity. CFD-predicted vorticity in the absence of a bubble agreed well with experimental observation. The CFD analysis indicated that the vorticity inside the cavity was not significantly changed when a single bubble was introduced. On this basis, the computed vorticity was utilized in describing the force balance applied to the attached particle. Computationally, it was found that the critical turbulence intensity, beyond which the particle was detached from the bubble, was 14%. This value was consistent with the experimental observation of detachment at Ti at 15.7%, and above, but not at lower values.
- Subject
- bubble; particle; turbulence intensity; vorticity; particle detachment; computational fluid dynamics (CFD)
- Identifier
- http://hdl.handle.net/1959.13/1477879
- Identifier
- uon:50050
- Language
- eng
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