Researchers at MIT have been working on making confined gas bubbles develop uniformly rather than in the usual random way. The team says that the formation of air bubbles in a liquid appears to be similar to the creation of liquid droplets from something like a dripping water faucet. However, the physics involved in each process is quite different.
The MIT scientists say that while water droplets are uniform in their size and spacing, bubble formation is a more random process. However, the team says that bubbles can be coaxed to form spheres as perfectly matched as water droplets. The findings seem mundane, but has implications for the development of microfluidic devices for biomedical research and for understanding how natural gas interacts with petroleum in the tiny pores inside underground rock formations.
The scientists found that the key to producing uniformly sized and spaced bubbles has to do with confining them to a narrow space. When air or gas is released into a large container of liquid, the dispersal of bubbles is scattershot. However, when released into a liquid confined in a relatively narrow tube, the gas produces a stream of bubbles perfectly matched in size and forming at even intervals.
The process of forming bubbles or droplets is similar and starts with an elongation of the flowing material that thins, and a pinch-off of the neck to produce bubble or droplet. The team performed experiments using gas percolating onto viscous liquids such as oil. In an unconfined space, the bubbles produced are unpredictable, but when in a tube formation is different.
Up to a certain point, the size and shape of the tube doesn’t matter. The team says that the findings have potential applications in a variety of practical settings, including inkjet printing, medical imaging, and making particulate materials.