Development and optimization of acoustic bubble structures at high frequencies
Lee, J, Ashokkumar, M, Yasui, K, Tuziuti, T, Kozuka, T, Towata, A and Iida, Y (2011) Development and optimization of acoustic bubble structures at high frequencies Ultrasonics Sonochemistry, 18 (1). pp. 92-98.
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At high ultrasound frequencies, active bubble structures are difficult to capture due to the decrease in timescale per acoustic cycle and size of bubbles with increasing frequencies. However the current study demonstrates an association between the spatial distribution of visible bubbles and that of the active bubble structure established in the path of the propagating acoustic wave. By monitoring the occurrence of these visible bubbles, the development of active bubbles can be inferred for high frequencies. A series of still images depicting the formation of visible bubble structures suggest that a strong standing wave field exists at early stages of wave propagation and weakens by the increase in the attenuation of the acoustic wave, caused by the formation of large coalesced bubbles. This attenuation is clearly demonstrated by the occurrence of a force which causes bubbles to be driven toward the liquid surface and limit standing wave fields to near the surface. This force is explained in terms of the acoustic streaming and traveling wave force. It is found that a strong standing wave field is established at 168 kHz. At 448 kHz, large coalesced bubbles can significantly attenuate the acoustic pressure amplitude and weaken the standing wave field. When the frequency is increased to 726 kHz, acoustic streaming becomes significant and is the dominant force behind the disruption of the standing wave structure. The disruption of the standing wave structure can be minimized under certain pulse ON and OFF ratios.
|Subjects :||Chemical and Process Engineering|
|Divisions :||Faculty of Engineering and Physical Sciences > Chemical and Process Engineering|
|Date :||1 January 2011|
|Identification Number :||10.1016/j.ultsonch.2010.03.004|
|Copyright Disclaimer :||Copyright 2010 Elsevier B.V.|
|Uncontrolled Keywords :||Science & Technology, Technology, Physical Sciences, Acoustics, Chemistry, Multidisciplinary, Chemistry, ACOUSTICS, CHEMISTRY, MULTIDISCIPLINARY, Ultrasound frequency, Acoustic bubble structure, Radiation forces, Attenuation, Bubble coalescence, Surfactants, PULSED ULTRASOUND, MULTIBUBBLE SONOLUMINESCENCE, SONOCHEMICAL EFFICIENCY, ULTRAFILTRATION MEMBRANES, CAVITATION BUBBLES, AQUEOUS-SOLUTION, CHEMICAL ACTION, ACTIVE ZONES, AIR BUBBLES, ENHANCEMENT|
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|Additional Information :||Item not available from this repository|
|Depositing User :||Symplectic Elements|
|Date Deposited :||19 Jul 2016 15:24|
|Last Modified :||19 Jul 2016 15:24|
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