title: Drainage of single Plateau borders: direct observation of rigid and mobile interfaces.
abstract: Foam drainage varies with surfactant. We present direct measurements of the flow velocity profiles across single Plateau borders, which make up the interconnected channel-like network for liquid flow. For protein foams the interface is rigid, whereas small-surfactant foams show significant interfacial mobility. The results agree with a model that takes into account the shearing of the liquid-gas interface transverse to the flow direction. A significant consequence is that bubble size and liquid volume fraction in a foam affect the relative importance of surface rheology on the drainage behavior.
authors.affiliation: Division of Engineering and Applied Sciences, Pierce Hall, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Stephan A
authors.initials: SA
authors.lastname: Koehler
authors.forename: Sascha
authors.initials: S
authors.lastname: Hilgenfeldt
authors.forename: Eric R
authors.initials: ER
authors.lastname: Weeks
authors.forename: Howard A
authors.initials: HA
authors.lastname: Stone