Foams

Abstract

Aqueous foams are studied both as materials with many applications, and as model systems for fields ranging from metallurgy to mathematics to biology. They are complex fluids with unique and unusual properties, exemplified as much by their multiscale structure as by the dynamical processes through which they evolve and even their dual liquid-like and solid-like behaviour. In this book, readers can easily find clear, up-to-date answers to their questions regarding the physical and physico-chemical properties of aqueous foams, explained using current knowledge of their structure, their stability, and their rheology. Newcomers to the field will find descriptions of numerous applications of foams in daily life and in industrial processes, the definition of basic concepts, hundreds of figures, and simple experiments to perform at home. Those who want to proceed further will find updated references, exercises with solutions, appendices with experimental and numerical techniques, and boxed text with the further mathematical detail.

Statistics and topological changes in 2D foam from the dry to the wet limit

“…For these we can benefit from both straightforward models and reliable F o r P e e r R e v i e w O n l y numerical methods. More recently, attention has moved to the case of wet foams [2,3], which pose new challenges.…”

Damping of liquid sloshing by foams

“…43 Glycerol is used to slow down the aging of the foam associated with the drainage and the coarsening processes. 30 In addition, the experiments are performed on short time scales, typically less than few minutes, to avoid such aging. The bubbles are generated using a 1.3 mm inner diameter needle and a syringe pump operating at constant flow rate, Q = 20 µL.min −1 .…”

“…29 In this regime, the effective viscosity of a foam is much larger than the viscosity of the foaming solution. 30,31 Therefore, foam is a good candidate to damp sloshing and thus to decrease the pressure forces exerted on the walls of a container.…”

Simulations of bubble division in the flow of a foam past an obstacle in a narrow channel

“…We choose a simple channel shape to try and extract something fundamental about flows such as these, rather than trying to explain any particular situation. We choose to work in 2D because it is possible to see clearly what shapes the lamellae take and because the simulations are relatively quick; moreover, it has been shown in the past [1] that 2D theory, simulations and experiments can say something useful about real, three-dimensional foams. Finally, by simulating motion at the scale of individual lamellae, we can take advantage of the well-defined local geometry found in equilibrium dry foams to generate highly accurate, if idealized, results.…”