| dc.description.abstract | The study of the interaction between particles and fluid-fluid interfaces is essential to a variety of applications. A systematic way to understand those phenomena is to consider them in two different limits: single particle versus multiple particles. One particular example of a single particle problem is the particle’s interaction with an acoustic bubble. Many bubble-based systems use oscillating microbubbles to trap particles, which further leads to applications including live animal trapping and cell manipulation. On the other hand, when multiple particles are involved, the study of the suspension injection and drainage has drawn much attention, which has the implication in biotechnology and food processing.
The objective of this research is to study and gain a fundamental understanding of the coupled dynamics between particles and fluid-fluid interfaces via experimental and theoretical approaches. First, we work on a project with a single-particle trapping via acoustic bubble. In this work, we quantify the magnitudes of secondary radiation force exerted by the oscillating bubble inside a microchannel for varying actuation frequencies and voltages. By combining well-developed theories that connect bubble oscillation yielding secondary radiation force to the acoustic actuation, we derive the expression to predict the critical input voltage that leads to particle release into the flow, which agrees with the experimental results.
The next phase of the research emphasizes the dynamics of the collection of particles. We experimentally investigate the effect of particle concentration on the viscous fingering behavior when the suspension is withdrawn from a Hele-Shaw cell. In particular, we quantify the fingering growth rate with varying initial particle concentrations. Our results reveal that the fingering growth rate increases with increasing particle concentrations, while the total drainage time also appears to be increasing. This successfully proves that the drainage efficiency is enhanced due to the presence of the particles. In addition, we observe the particles entrained into the thin film on the plate after drainage, which also varies with the particle concentration and the ratio between gap thickness and particle diameter. Using a simplified model, we also find an entrainment criterion in agreement with the experimental results. | en |
