Daniels Nonlinear Lab

Dept of Physics

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Thin Fluid Flows The spreading of surfactants on thin films is an industrially and medically important phenomenon, but the dynamics are highly nonlinear and visualization of the surfactant dynamics has been a long-standing experimental challenge. Our mathematics collaborators, Michael Shearer and Rachel Levy perform modelling and analysis of these same systems. We perform quantitative measurements of the spreading of an insoluble surfactant on a thin layer of glycerin. During the spreading process, we directly observe both the radial height profile of the spreading droplet (red line) and the spatial distribution of the fluorescently-tagged surfactant (green intensity). We find that the spreading circular layer of surfactant forms a capillary ridge at its leading edge with a trough trailing the ridge. Both the capillary ridge and surfactant leading edge can be described to spread as R ~ t1/4 . Movies of the spreading process. Publications D. W. Fallest, C. Fox, and K. E. Daniels. Fluorescent visualization of a spreading surfactant. (Under review) [PDF]

:: Updated: 27 Oct 2009 :: LABlog (restricted) :: Copyright © 2009 by Daniels Lab ::