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Soluble surfactant spreading on spatially confined thin liquid films

Journal Article

Hanyak, M., Sinz, D.K.N. & Darhuber, A.A. (2012). Soluble surfactant spreading on spatially confined thin liquid films. Soft Matter, 8(29), 7660-7671. in Web of Science Cited 3 times

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Abstract

We studied the spreading of soluble surfactants on spatially confined thin liquid films by means of

comprehensive experiments and numerical simulations. We determined the time evolution of the liquid

film thickness both from interference microscopy measurements and finite element calculations. A

characteristic rim develops ahead of the spreading surfactant front. Within certain time intervals, the

rim position can be well represented by a power-law relation xrim z ta. The corresponding spreading

exponent a depends on the method of surfactant deposition and the numerical values deduced from

experiments and simulations quantitatively agree. Depth-resolved simulations that account for domain

deformability using the Arbitrary Lagrangian–Eulerian method show that shear-induced concentration

non-uniformities across the rim film thickness tend to reduce the rim height. Fingering instabilities that

are frequently observed in experiments were qualitatively reproduced in the simulations.