A numerical study of the shape mode oscillation of microbubbles in a viscous compressible liquid

Corbett, Callan ORCID: 0000-0002-7922-4562 (2023). A numerical study of the shape mode oscillation of microbubbles in a viscous compressible liquid. University of Birmingham. Ph.D.

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Recent experiments (Vyas et al. [2020]) have revealed the interesting cleaning effects that take place due to the shape mode oscillation of bubbles over a rigid boundary. Whilst a microbubble was undertaking shape oscillation moving over a bacterial biofilm, it removed the contaminants from the boundary and created a clean path through the biofilm. This demonstrated much higher cleaning efficiency than that associated with the volume oscillation of cavitation bubbles. Hence, the shape mode oscillation of bubbles near to a rigid boundary proves to be an important topic of research and the main topic of this thesis. The viscous, weakly compressible boundary integral method (VCBIM) is initially described and validated against analytical, numerical, and experimental results, achieving excellent agreement. The characteristics of a microbubble in shape oscillation are then studied, finding that the rigid boundary decreases the natural frequency of the modes. It is found that shape oscillation of a nearby bubble generates a significantly larger amount of shear stress on a rigid boundary, agreeing with experimental observations. This exemplifies the applicability of shape oscillation to ultrasonic cleaning. Additionally, the effects of a surfactant on bubble oscillation are examined. The presence of a surfactant is found to have a significant effect on the shape oscillation of bubbles, as well as greatly increasing the shear stress generated on a rigid boundary. Thus, it is found that the presence of a surfactant enhances the cleaning of a surface by the shape oscillation of a nearby bubble.

Type of Work: Thesis (Doctorates > Ph.D.)
Award Type: Doctorates > Ph.D.
Licence: All rights reserved
College/Faculty: Colleges (2008 onwards) > College of Engineering & Physical Sciences
School or Department: School of Mathematics
Funders: Engineering and Physical Sciences Research Council
Subjects: Q Science > QA Mathematics
URI: http://etheses.bham.ac.uk/id/eprint/13404


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