The viscoelastic effects on the evolution of a three-dimensional microbubble

O'Brien, Eoin Nicholas ORCID: 0009-0003-8632-0063 (2023). The viscoelastic effects on the evolution of a three-dimensional microbubble. University of Birmingham. Ph.D.

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Abstract

Bubbles often appear in non-Newtonian liquids from nature, engineering, to biomedical applications, but their study has been under researched compared to their Newtonian counterpart. Here we extend the axisymmetric modelling of Lind and Phillips (Lind and Phillips [2010a,b, 2013]) to three-dimensional modelling. The approach is based on the boundary integral method coupled with Maxwell’s constitutive equation and Jeffrey’s constitutive equation. The flow is assumed to have moderate to high Reynolds number and thus is irrotational in the bulk domain. The viscoelastic effects are incorporated approximately in the normal stress balance at the bubble surface. The numerical model has excellent agreement with the
corresponding Rayleigh-Plesset equation for spherical bubbles in a non-Newtonian liquid. Computations are carried out for a bubble near a corner at various angles. The numerical results agree very well with the experiments for bubbles in a Newtonian fluid in a corner. For a Maxwell fluid/Jeffrey fluid, as the Deborah number, De, increases/viscosity ratio, β decreases, the amplitude and period of the bubble oscillation increase, the bubble migration to the corner enhances, and the bubble jet is broader, flatter and inclined more to the further boundary. This implies an
improvement to surface cleaning of all surrounding boundaries for ultrasonic cavitation cleaning and results in greater administration of noninvasive therapy and drug
delivery.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):