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Dynamics and Stability of Surfactant Coated thin Spreading Films

Published online by Cambridge University Press:  10 February 2011

Omar K. Matar
Affiliation:
Department of Chemical Engineering, Princeton University, Princeton NJ 08544–5263
Sandra M. Troian
Affiliation:
Department of Chemical Engineering, Princeton University, Princeton NJ 08544–5263
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Abstract

Within lubrication theory, we investigate the hydrodynamic stability of a thin surfactant coated liquid film spreading strictly by Marangoni stresses. These stresses are generated along the air-liquid interface because of local variations in surfactant concentration. The evolution equations governing the unperturbed film thickness and surface surfactant concentration admit simple self-similar solutions for rectilinear geometry and global conservation of insoluble surfactant. A linear stability analysis of these self-similar flows within a quasi steady-state approximation (QSSA) yields an eigenvalue problem for a single third-order nonlinear differential equation. The analysis indicates that a thin film driven purely by Marangoni stresses is linearly stable to small perturbations of all wavenumbers. The insights gained from this calculation suggest a flow mechanism that can potentially destabilize the spreading process.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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References

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