Breward, C. J. W. and Darton, R. C. and Howell, P. D. and Ockendon, J. R. (2001) The effect of surfactants on expanding free surfaces. Chemical Engineering Science, 56 . pp. 2867-2878.
Official URL: http://www.elsevier.com/wps/find/journaldescriptio...
This paper develops a systematic theory for the flow observed in the so-called ``overflowing cylinder'' experiment. The basic phenomenon to be explained is the order of magnitude increase in the surface velocity of a slowly overflowing beaker of water that is caused by the addition of a small amount of soluble surfactant. We perform analyses of (i) an inviscid bulk flow in which diffusion is negligible, (ii) a hydrodynamic boundary layer in which viscous effects become important, (iii) a diffusive boundary layer where diffusion is significant, and by matching these together arrive at a coupled problem for the liquid velocity and surfactant concentration. Our model predicts a relation between surface velocity and surface concentration which is in good agreement with experiment. However a degeneracy in the boundary conditions leaves one free parameter which must be taken from experimental data. We suggest an investigation that may resolve this indeterminacy.
|Subjects:||D - G > Fluid mechanics|
|Research Groups:||Oxford Centre for Industrial and Applied Mathematics|
|Deposited By:||Peter Howell|
|Deposited On:||04 Aug 2004|
|Last Modified:||20 Jul 2009 14:18|
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