B.S. Mechanical Engineering, PUC-Rio, Brazil, 2012
M.S. Mechanical Engineering, PUC-Rio, Brazil, 2014
A foam is a substance that is formed by trapping pockets of gas in a liquid. Some examples of foams are ice cream and a glass of beer. In the latter case a foam is formed by bubbles raising through a liquid and being collected at the interface. The height, density and lifetime of the foam are strongly dependent on the properties of the surface active compounds that are present in the liquid. When the bubble approaches the interface it forms a thin film of liquid that drains and eventually burst. The deformation of the bubble with time as it approaches the interface is captured by a camera. From the interference patterns seen it is possible to estimate the behavior of the drainage of the film of liquid. During the experiment the pressure inside the bubble is also recorded as it deforms.
A similar experiment is being developed to work with emulsions. An emulsion is a mixture of two or more immiscible liquids, such as oil and water. Oily water emulsion are one of the main pollutants emitted into water by industry and domestic sewage. Traditional techniques used in separation of unwanted oil-in-water emulsions have an important coalescence step. Using a similar setup, we want to understand better this coalescence step.