Soluble surfactant spreading on spatially confined thin liquid films
Hanyak, Myroslava, Sinz, David & Darhuber, Anton (2012). Soluble surfactant spreading on spatially confined thin liquid films. Soft Matter, 8(29), 7660-7671.
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.