| Tue January 6th 2009 16:00 ZH286 | Seminar | Decoupling of Marangoni flow translation and capillary spreading of a droplet Roger Jeurissen |
Details:When a droplet moves over a solid substrate, whether by gravity, shear due to air flow, or inertia, the droplet spreads. Typically, the order of magnitude of the spreading speed is coupled to the translational speed. However, when a droplet is moved by surfactant driven Marangoni flow, the spreading speed and the translation speed are completely decoupled. We investigate this unique regime in which the time scale of droplet translation is many orders of magnitude larger or smaller, depending on the droplet size, than the spreading speed. We find that the surface divergence of the velocity in thin film Marangoni flow vanishes. As examples of how these results make flows tractable by analytical methods, the translation of a ridge and the development of a fingering instability are analyzed. The analysis of the fingering instability is corroborated by an experimental observation of the fingering instability. | ||
