Microbubble dynamics near rigid boundaries

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Mahmud, Mehdi Hassan (2020). Microbubble dynamics near rigid boundaries. University of Birmingham. Ph.D.

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Abstract

This thesis is concerned with the interaction of a microbubble with rigid boundaries. This phenomenon is associated with comprehensive and critical applications such as cavitation erosion, cavitation cleaning, sonochemistry, biomedical ultrasonics and underwater explosions. Our numerical model is based on the viscous potential theory coupled with the boundary integral method. The Lagrangian time integration is used to update the bubble surface and the potential on the bubble surface. We described the physical, mathematical and numerical model for bubble dynamics. A Post-Processor was implemented for displaying bubble motion, velocity field and pressure contour. Three typical cases have been investigated. The first case is for a bubble at a corner consisting of two flat rigid walls. The Green function is obtained, satisfying the impenetrable conditions at the rigid walls using the method of images. The computational results agree well with the experimental data. Parametric studies were accomplished in terms of bubble stand-off distances from the two walls, corner angles, etc. The second case is for the interaction of a microbubble with a suspended spherical particle based on a nonlinear interaction model. The computational results are again in good agreement with the experimental results for this case. Our computations show that the particle and the bubble move away during expansion and move back during the collapse stage. The third case is a bubble in a circular cylinder. The model was firstly validated with experimental data. Numerical analyses were performed in terms of the tube radius, tube length, the eccentricity of the bubble from the axis of the symmetry, etc.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):