Contributions to the acoustic excitation of bubbles released
from a nozzle
Contributions to the acoustic excitation of bubbles released
from a nozzle
It has recently been demonstrated that air bubbles released from a nozzle are excited into volume
mode oscillations by the collapse of the neck of air formed at the moment of bubble detachment. A
pulse of sound is caused by these breathing mode oscillations, and the sound of air-entraining flows
is made up of many such pulses emitted as bubbles are created. This paper is an elaboration on a
JASA-EL paper, which examined the acoustical excitation of bubbles released from a nozzle. Here,
further details of the collapse of a neck of air formed at the moment of bubble formation and its
implications for the emission of sound by newly formed bubbles are presented. The role of fluid
surface tension was studied using high-speed photography and found to be consistent with a simple
model for neck collapse. A re-entrant fluid jet forms inside the bubble just after detachment, and its
role in acoustic excitation is assessed. It is found that for slowly-grown bubbles the jet does make
a noticeable difference to the total volume decrease during neck collapse, but that it is not a
dominant effect in the overall acoustic excitation.
2625-2634
Czerski, H.
7d291075-9bab-46f8-9005-21b31220b96a
Deane, Grant
be682612-ecac-44e1-9db2-23ee5123fb6f
2010
Czerski, H.
7d291075-9bab-46f8-9005-21b31220b96a
Deane, Grant
be682612-ecac-44e1-9db2-23ee5123fb6f
Czerski, H. and Deane, Grant
(2010)
Contributions to the acoustic excitation of bubbles released
from a nozzle.
Journal of the Acoustical Society of America, 128 (5), .
(doi:10.1121/1.3484087).
Abstract
It has recently been demonstrated that air bubbles released from a nozzle are excited into volume
mode oscillations by the collapse of the neck of air formed at the moment of bubble detachment. A
pulse of sound is caused by these breathing mode oscillations, and the sound of air-entraining flows
is made up of many such pulses emitted as bubbles are created. This paper is an elaboration on a
JASA-EL paper, which examined the acoustical excitation of bubbles released from a nozzle. Here,
further details of the collapse of a neck of air formed at the moment of bubble formation and its
implications for the emission of sound by newly formed bubbles are presented. The role of fluid
surface tension was studied using high-speed photography and found to be consistent with a simple
model for neck collapse. A re-entrant fluid jet forms inside the bubble just after detachment, and its
role in acoustic excitation is assessed. It is found that for slowly-grown bubbles the jet does make
a noticeable difference to the total volume decrease during neck collapse, but that it is not a
dominant effect in the overall acoustic excitation.
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Published date: 2010
Additional Information:
This paper describes detailed experiments supporting a new theory for the mechanism driving newly-produced bubbles to produce sound. The insights provided by this research enable a new type of experiment, where the sound produced by bubbles being formed can provide dynamical information about the bubble formation event. This is important for oceanography and chemical engineering, where the bubbles formed in turbulent environments control the overall effects of a complex system. The results described in this paper are already being used directly to understand the bubbles underneath breaking waves, and their effects on gas flux across the air-sea interface.
Organisations:
Fluid Dynamics & Acoustics Group
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Local EPrints ID: 182401
URI: http://eprints.soton.ac.uk/id/eprint/182401
ISSN: 0001-4966
PURE UUID: afc7852c-a6d4-4ad5-964f-bc2b582fd1f3
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Date deposited: 28 Apr 2011 08:48
Last modified: 14 Mar 2024 02:59
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Contributors
Author:
H. Czerski
Author:
Grant Deane
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