Foams: form and flow
By: Simon Cox
From: Institute of Mathematics and Physics, Aberystwyth University,
United Kingdom
At: Complexo Interdisciplinar, Anfiteatro
[2009-01-28]
When soap bubbles agglomerate, they do so in a highly organized way. The local geometry of the resulting structure, as dictated by Plateau laws, is also reminiscent of various biological structures. In the first part of this talk, I will describe the physics behind bubble structure and explore the analogies with cellular organisation in biology. Foams, that is collections of bubbles, are found in many situations: industrially they are used in oil extraction from porous media and for ore separation in mining, while domestically they are important in foods and cosmetic products. Being able to predict their behaviour under a given perturbation stimulates improved efficiency of industrial processes and the possibility to relate chemical formulation to rheology and hence to consumer satisfaction. In the second part of the talk I will show how the bubble-scale structure can be used as the basis for modelling the flow of foams in a number of scenarios. In particular, I will give examples of shear and contraction flows and the emerging field of discrete microfluidics in which foams are confined within narrow channels. In all these cases, correctly modelling the dissipation mechanisms is the key to accurately predicting the material response.