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Yeo Cheon (Joseph) Kim    LinkedIn

PhD Candidate, University of New South Wales, Australia.


PhD Topic:

"Controlled generation, and acoustic-driven translation, of single microbubbles"

Research interests: Biomedical devices, acoustics, microfluidics, mathematical modelling, microbubble, PIV, computational fluid dynamics


Current project: Tomographic PIV on Myocardial Bridging

To be added

PhD: Controlled generation, and acoustic-driven translation, of single microbubbles


Microbubbles can be beneficially used for froth flotation, water treatment, food processing, foam fabrication, diagnostic, therapeutic applications. Alternatively, microbubbles need to be removed from microfluidic flow paths and biological systems. This thesis aims to significantly advance our fundamental and practical understanding of how pulsed pressure inputs can be harnessed to control the formation and translation of microbubbles. Since the underlying physics of pressure pulse/bubble interactions are not well-understood in the literature, this thesis reports new theoretical, experimental, and numerical analysis methods for making, moving and removing single microbubbles, using various forms of pressure pulses.

To gain insight into the dynamics of making microbubbles at the air/liquid/solid interface, a new bubble generation technique was developed, consisting of a pressure pulse controller and a micropipette (orifice sizes ~0.6μm) within an external co-flow. This innovative gas injection method controllably generated single microbubbles in the range 62.6-150.8 μm during systematic testing.

In moving microbubbles, an experimentally validated transient numerical model was developed to gain insights into bubble translations when driven by pulsed ultrasonic waves. The results revealed that the added mass force, gained through the on-period of the pulse, continued to drive the bubble throughout the off-period, enabling a large total displacement even in the case of low duty-cycle (2%).

Finally, ultrasonically driven bubble-wall interactions were examined under various conditions of channel flow (bubble size, flow rate, acoustic pressure amplitudes) to aid the development of microbubble removing systems. A comparison of the observations with theory revealed three distinct regimes: free bubble translation, on-wall bubble translation and bubble-wall attachment. It was found that the acoustic radiation force needs to be at least 0.2 nN greater than the combined maximum repulsive forces of the shear lift and wall

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