Bubble scavenging in Hele-Shaw cell

When a bubble rises in a suspension of microscopic particles, the particles that collide with the bubble can stick to it and be brought to the surface, a process used to separate microparticles in a variety of industrial processes ranging from wastewater recovery to mineral flotation. Previous experiments and models for bubble scavenging have focused on bubbles rising in unconfined flow and in narrow microfluidic channels. However, precisely how scavenging is affected by confinement in only a single direction is largely unknown. In this study, experiments and theoretical analysis are carried out for bubble scavenging in a gap, or Hele-Shaw cell, for various gap distances. A novel approach was developed to measure the particles collected by a single bubble by allowing the bubbles to pop and transport these particles to a glass plate where they can be counted. The experiments reveal that the scavenging efficiency increases as the gap narrows up to a factor of four for a gap that is slightly larger than the bubble diameter. To understand these results, a numerical simulation of the flow field around the bubbles for different confinement gaps. An analytical expression is developed for the scavenging efficiency based on a combination of 2D and 3D potential flow, and other factors such as the bubble shape and trajectory are evaluated.

Author dc:creator

• Wang, Yizhao

Advisor dc:contributor.advisor

• Bird, James

• Engineering

Statement dc:rights

• Attribution 4.0 International

Licence dc:rights.uri

• http://creativecommons.org/licenses/by/4.0/

Language dc:language.iso

en_US

Handle dc:identifier.uri

https://hdl.handle.net/2144/46265

OAI identifier oai:identifier

oai:open.bu.edu:2144/46265