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Free-Lagrange simulations of the expansion and jetting collapse of air bubbles in water

Free-Lagrange simulations of the expansion and jetting collapse of air bubbles in water
Free-Lagrange simulations of the expansion and jetting collapse of air bubbles in water
A free-Lagrange numerical method is implemented to simulate the axisymmetric jetting collapse of air bubbles in water. This is performed for both lithotripter shock-induced collapses of initially stable bubbles, and for free-running cases where the bubble initially contains an overpressure. The code is validated using two test problems (shock-induced bubble collapse using a step shock, and shock–water column interaction) and the results are compared to numerical and experimental results. For the free-running cases, simulations are conducted for a bubble of initial radius 0.3 mm located near a rigid boundary and near an aluminium layer (planar and notched surfaces). The simulations suggest that the boundary and its distance from the bubble influence the flow dynamics, inducing bubble elongation and jetting. They also indicate stress concentration in the aluminium and the likelihood of aluminium deformation associated with bubble collapse events. For the shock-induced collapse, a lithotripter shock, consisting of 56 MPa compressive and ?10 MPa tensile waves, interacts with a bubble of initial radius 0.04 mm located in a free field (case 1) and near a rigid boundary (case 2). The interaction of the shock with the bubble causes it to involute and a liquid jet is formed that achieves a velocity exceeding 1.2 km s?1 for case 1 and 2.6 km s?1 for case 2. The impact of the jet on the downstream wall of the bubble generates a blast wave with peak overpressure exceeding 1 GPa and 1.75 GPa for cases 1 and 2, respectively. The results show that the simulation technique retains sharply resolved gas/liquid interfaces regardless of the degree of geometric deformation, and reveal details of the dynamics of bubble collapse. The effects of compressibility are included for both liquid and gas phases, whereas stress distributions can be predicted within elastic–plastic solid surfaces (both planar and notched) in proximity to cavitation events. There is a movie with the online version of the paper.
shock waves, bubble dynamics, cavitation
0022-1120
1-25
Turangan, C.K.
dad59b33-a4d7-4ac6-a49c-006e443e8ba4
Jamaluddin, A.R.
80faf5ed-1643-4c14-abaf-a1affcac9cf7
Ball, G.J.
2eb541a1-2a56-44c4-8ab1-4ff035fe87b7
Leighton, T.G.
3e5262ce-1d7d-42eb-b013-fcc5c286bbae
Turangan, C.K.
dad59b33-a4d7-4ac6-a49c-006e443e8ba4
Jamaluddin, A.R.
80faf5ed-1643-4c14-abaf-a1affcac9cf7
Ball, G.J.
2eb541a1-2a56-44c4-8ab1-4ff035fe87b7
Leighton, T.G.
3e5262ce-1d7d-42eb-b013-fcc5c286bbae

Turangan, C.K., Jamaluddin, A.R., Ball, G.J. and Leighton, T.G. (2008) Free-Lagrange simulations of the expansion and jetting collapse of air bubbles in water. Journal of Fluid Mechanics, 598, 1-25. (doi:10.1017/S0022112007009317).

Record type: Article

Abstract

A free-Lagrange numerical method is implemented to simulate the axisymmetric jetting collapse of air bubbles in water. This is performed for both lithotripter shock-induced collapses of initially stable bubbles, and for free-running cases where the bubble initially contains an overpressure. The code is validated using two test problems (shock-induced bubble collapse using a step shock, and shock–water column interaction) and the results are compared to numerical and experimental results. For the free-running cases, simulations are conducted for a bubble of initial radius 0.3 mm located near a rigid boundary and near an aluminium layer (planar and notched surfaces). The simulations suggest that the boundary and its distance from the bubble influence the flow dynamics, inducing bubble elongation and jetting. They also indicate stress concentration in the aluminium and the likelihood of aluminium deformation associated with bubble collapse events. For the shock-induced collapse, a lithotripter shock, consisting of 56 MPa compressive and ?10 MPa tensile waves, interacts with a bubble of initial radius 0.04 mm located in a free field (case 1) and near a rigid boundary (case 2). The interaction of the shock with the bubble causes it to involute and a liquid jet is formed that achieves a velocity exceeding 1.2 km s?1 for case 1 and 2.6 km s?1 for case 2. The impact of the jet on the downstream wall of the bubble generates a blast wave with peak overpressure exceeding 1 GPa and 1.75 GPa for cases 1 and 2, respectively. The results show that the simulation technique retains sharply resolved gas/liquid interfaces regardless of the degree of geometric deformation, and reveal details of the dynamics of bubble collapse. The effects of compressibility are included for both liquid and gas phases, whereas stress distributions can be predicted within elastic–plastic solid surfaces (both planar and notched) in proximity to cavitation events. There is a movie with the online version of the paper.

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More information

e-pub ahead of print date: 25 February 2008
Published date: March 2008
Keywords: shock waves, bubble dynamics, cavitation

Identifiers

Local EPrints ID: 51039
URI: https://eprints.soton.ac.uk/id/eprint/51039
ISSN: 0022-1120
PURE UUID: e9551cb0-e469-447a-a5b3-f692d63e0a20
ORCID for T.G. Leighton: ORCID iD orcid.org/0000-0002-1649-8750

Catalogue record

Date deposited: 01 May 2008
Last modified: 10 Sep 2019 00:54

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Contributors

Author: C.K. Turangan
Author: A.R. Jamaluddin
Author: G.J. Ball
Author: T.G. Leighton ORCID iD

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