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Microbubble Generation via Combined Saffman-Taylor and Plateau-Rayleigh Instabilities

Citation

Cook, S and Barbaca, L and Russell, PS and Venning, JA and Pearce, BW and Brandner, PA, Microbubble Generation via Combined Saffman-Taylor and Plateau-Rayleigh Instabilities, Proceedings of the 23rd Australasian Fluid Mechanics Conference, 04-08 December 2022, Sydney, pp. AFMC2022-273. ISSN 2653-0597 (2022) [Refereed Conference Paper]


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Abstract

Microbubble generation via rapid depressurization of supersaturated water through a 8 mm wide by 2 mm long by 0.1 mm deep Hele-Shaw passage was explored experimentally using micro shadowgraphy. The flow topology consists of a series of regularly sized cellular cavities, characteristic of viscous fingering in a Hele-Shaw flow. Cells develop in a region of separated flow at the sharp leading edge of the confined flow. Each cell is stable and pinned to the wall. Small-scale structures stretch into ligaments downstream and destabilise due to Plateau-Rayleigh instability, with consequent microbubble pinch-off providing a coherent bubble stream from each cell. The influence of cavitation number (σin j) and Reynolds number (Re) on instability formation and microbubble production is investigated by varying the differential pressure between the passage inlet and outlet. Optimum conditions for bubble generation were found for σinj = 0.28 − 0.65 and coincide with the maximum in the number of cells forming along the passage leading edge. Polydisperse bubble populations were generated for all conditions. Bubble production rates of up to 2.2 MHz were observed, with a dominant bubble size of ≈ 6Ám. Further decrease in σinj hindered bubble generation due to disappearance of the laminar instability as the flow in the passage transitions to a turbulent regime.

Item Details

Item Type:Refereed Conference Paper
Keywords:microbubble generation, microfluidics, nuclei, Hele-Shaw cell
Research Division:Engineering
Research Group:Maritime engineering
Research Field:Ship and platform structures (incl. maritime hydrodynamics)
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in engineering
UTAS Author:Cook, S (Miss Sienna Cook)
UTAS Author:Barbaca, L (Dr Luka Barbaca)
UTAS Author:Russell, PS (Mr Patrick Russell)
UTAS Author:Venning, JA (Dr James Venning)
UTAS Author:Pearce, BW (Dr Bryce Pearce)
UTAS Author:Brandner, PA (Professor Paul Brandner)
ID Code:154809
Year Published:2022
Deposited By:NC Maritime Engineering and Hydrodynamics
Deposited On:2023-01-09
Last Modified:2023-01-16
Downloads:0

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