Wetting and contact angle hysteresis on chemically patterned surfaces in two dimensionsare analyzed from a stationary phase-field model for immiscible two phase fluids. We first study the sharp-interface limit of the model by the method of matched asymptotic expansions. We then justify the results rigorously by the γ-convergence theory for the related variational problem and study the properties of the limiting minimizers. The results also provide a clear geometric picture of the equilibrium configuration of the interface. This enables us to explicitly calculate the total surface energy for the two phase systems on chemically patterned surfaces with simple geometries, namely the two phase flow in a channel and the drop spreading. By considering the quasi-staticmotion of the interface described by the change of volume (or volume fraction), we can follow the change-of-energy landscape which also reveals the mechanism for the stick-slip motion of the interface and contact angle hysteresis on the chemically patterned surfaces. As the interface passes throughpatterned surfaces, we observe not only stick-slip of the interface and switching of the contact angles but also the hysteresis of contact point and contact angle. Furthermore, as the size of the patternde creases to zero, the stick-slip becomes weaker but the hysteresis becomes stronger in the sense that one observes either the advancing contact angle or the receding contact angle (when the interface ismoving in the opposite direction) without the switching in between. © 2011 Society for Industrial and Applied Mathematics.
|Original language||English (US)|
|Number of pages||27|
|Journal||SIAM Journal on Applied Mathematics|
|State||Published - Jan 2011|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): SA-C0040/UK-C0016
Acknowledgements: This work was supported in part by award SA-C0040/UK-C0016, made by King Abdullah University of Science and Technology (KAUST), by Hong Kong RGC-GRF grants 603107 and 604209, and by the National Basic Research Program of China under project 2009CB623200.This author's work was supported by NSFC project 11001260 and by the State Key Laboratory of Scientific and Engineering Computing of China.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.