Zhang, Yuning (Researcher in engineering) (2012) Analysis of radial oscillations of gas bubbles in Newtonian or viscoelastic mediums under acoustic excitation. PhD thesis, University of Warwick.

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Abstract

Acoustic cavitation plays an important role in a broad range of biomedical, chemical and oceanic engineering problems. For example, kidney stone can be crushed into the powder (being discharged naturally) by the acoustic cavitation generated by carefully controlled focused ultrasonic beams. Therefore, the prediction of generation of acoustic cavitation is essential to the aforementioned emerging non-invasive technique for kidney stone crushing. The objective of this PhD program is to study the generation of acoustic cavitation (e.g. through rectified mass diffusion across bubble interface) theoretically in the Newtonian fluids (e.g. water) or viscoelastic mediums (e.g. human soft tissue) under acoustic excitation of single or dual frequency. The compressibility and the viscosity of the liquid, heat and mass transfer across bubble-medium interface are all considered in this study.

During this PhD program, the established works in the literature on the
above topic have been re-examined. More physically general formulas of natural frequency and damping of gas bubble oscillations in Newtonian or viscoelastic mediums has been derived and further employed for solving the problem of bubble growth under acoustic field (i.e. rectified mass diffusion).

For rectified mass diffusion of gas bubbles in Newtonian liquids, the predictions have been improved for high-frequency region of megahertz and above. Effects of medium viscoelasticity and dual-frequency acoustic excitation on rectified mass diffusion have also been studied. To facilitate the fast growth of bubble under acoustic field, dynamic-frequency and dual-frequency techniques have been proposed and demonstrated.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QC Physics T Technology > TA Engineering (General). Civil engineering (General) T Technology > TP Chemical technology
Library of Congress Subject Headings (LCSH):	Cavitation, Bubbles, Diffusion, Compressibility, Oscillations, Damping (Mechanics), Viscoelasticity
Official Date:	November 2012
Dates:	Date Event November 2012 Submitted
Institution:	University of Warwick
Theses Department:	School of Engineering
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Li, Shengcai
Sponsors:	Engineering and Physical Sciences Research Council (EPSRC) (R.ESCM 9217); University of Warwick; Chinese Scholarship Council (CSC)
Extent:	xix, 156 leaves.
Language:	eng

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