Microstructural effects in aqueous foam fracture

We examine the fracture of a quasi-two-dimensional surfactant-laden aqueous foam under an applied driving pressure, using a network modelling approach developed for metallic foams by Stewart & Davis (J. Rheol., vol. 56, 2012, p. 543). In agreement with experiments, we observe two distinct mechan...

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Bibliographic Details
Published inJournal of fluid mechanics Vol. 785; pp. 425 - 461
Main Authors Stewart, Peter S., Davis, Stephen H., Hilgenfeldt, Sascha
Format Journal Article
LanguageEnglish
Published Cambridge, UK Cambridge University Press 25.12.2015
Subjects
Crystallization
Fluid mechanics
Microstructure
fingering instability
interfacial flows (free surface)
foams
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Summary:We examine the fracture of a quasi-two-dimensional surfactant-laden aqueous foam under an applied driving pressure, using a network modelling approach developed for metallic foams by Stewart & Davis (J. Rheol., vol. 56, 2012, p. 543). In agreement with experiments, we observe two distinct mechanisms of failure analogous to those observed in a crystalline solid: a slow ductile mode when the driving pressure is applied slowly, where the void propagates as bubbles interchange neighbours through the T1 process; and a rapid brittle mode for faster application of pressures, where the void advances by successive rupture of liquid films driven by Rayleigh–Taylor instability. The simulations allow detailed insight into the mechanics of the fracturing medium and the role of its microstructure. In particular, we examine the stress distribution around the crack tip and investigate how brittle fracture localizes into a single line of breakages. We also confirm that pre-existing microstructural defects can alter the course of fracture.
ISSN:0022-1120
1469-7645
DOI:10.1017/jfm.2015.636