Symmetry-to-asymmetry transition of Marangoni flow at a convex volatizing meniscus

Plenty of studies have been made to have a comprehensive understanding of heat and mass transport at an evaporating meniscus. Recently in this journal Gazzola et al. (2009) reported an asymmetrical flow pattern generated at a convex meniscus while the boundary conditions were symmetrical. In their experiment a vertical micro well was filled up with liquid and the meniscus was held convex above the well outlet. The flow pattern at the meniscus was found having only one single vortex, which was distinct from those symmetrical paired vortexes in literatures (Buffone and Sefiane 2004). In the present work a simulation is conducted to clarify the mechanisms behind the abnormality. Factors including liquid evaporation, vapor transport, and Marangoni effect are considered. It is found that for a convex meniscus as that in the experiment, symmetrical flow pattern is not stable. The transition of symmetry to asymmetry occurs and this is greatly affected by random perturbations. After the asymmetrical flow pattern is established, the perturbations have relatively minor effects on the flow pattern.