Hydrodynamics of Thin Viscous Films
01 Jan 2012-pp 59-87
TL;DR: In this paper, the authors introduce the concepts from hydrodynamics of thin films and explain how thin-film equations can be derived for different regimes of surface slip, as well as their application to experiments of dewetting polymer films.
Abstract: Chapter 4 mirrors Chap. 2 of Part I: while the latter developed the concepts from statistical mechanics, the present chapter introduces the concepts from hydrodynamics of thin films. While the key theoretical tool for the statistical mechanics aspects is the effective interface potential, a similar key role in the hydrodynamics of thin films is played by the lubrication approximation. Chapter 4 explains how thin film equations can be derived for different regimes of surface slip. Mathematical properties of the thin film equation and its numerics are discussed, as well as their application to experiments of dewetting polymer films.
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TL;DR: In this paper, a dry spot at the center of a silicone wafer was nucleated and the rate of growth was observed to be independent of R, independent of the film thickness, inversely proportional to the oil viscosity, and very sensitive to the value of the equilibrium contact angle between oil and wafer.
Abstract: Films of silicone oils (or alkanes) deposited on low-energy surfaces (grafted silicone wafers) are metastable. We nucleate a dry spot at the center of the wafer and observe the rate of growth V=dR/dt of the dry patch of radius R. We find that V is (a) independent of R, (b) independent of the film thickness, (c) inversely proportional to the oil viscosity, and (d) very sensitive to the value of ${\mathrm{\ensuremath{\theta}}}_{\mathit{e}}$, the equilibrium contact angle between oil and wafer. At small ${\mathrm{\ensuremath{\theta}}}_{\mathit{e}}$, V\ensuremath{\approxeq}${\mathrm{\ensuremath{\theta}}}_{\mathit{e}}^{3}$. All these features are in agreement with a recent hydrodynamic theory.
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