Bubble formation in selected industrial problems

Foam and bubbles are ubiquitous in industry and nature. They have a wide range of applications but are also an undesirable product of certain processes. This thesis considers two individual industrial problems with the common phenomenon of bubble and foam formation. Bubble nucleation is a phenomenon observed in many different physical situations from decompression sickness to champagne effervescence. It is of vital importance to the formation of a creamy head that is distinctive to stout beers. I present experimental work that demonstrates that cellulose fibres can be used to initiate stout beers and could serve as an alternative to widget technology. I derive mathematical models for the various gas pocket geometries I observed in cellulose fibres that produce bubbles when submerged in stout beer. These models are solved and compared to experimental results where possible to give the first quantitative evaluation of the current models of bubble nucleation. I present the work done to model a novel design for accurate volume measurement of milk. The new design proposes a modification of the air elimination vessel used in current milk pumping systems to increase accuracy by preventing air bubbles being pumped with milk. We consider the operation of the entire system to pump milk, the flow of milk inside the air elimination vessel, the entrainment of air bubbles into a pool of milk and the drainage of foam.