Simulated Contact Angle Hysteresis of a Three-Dimensional Drop on a Chemically Heterogeneous Surface: A Numerical Example

✍ Scribed by Simon Brandon; Amir Wachs; Abraham Marmur

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 346 KB
• Volume: 191
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1997.4912

✦ Synopsis

the contact line is predicted without any a priori assumptions A public domain software package is employed in the quasiof ''pinning'' of the contact line at certain locations on the steady-state simulation of contact angle hysteresis. Three-dimensurface.

sional sessile drops in equilibrium with a model chemically hetero-Two-dimensional simulations, however, provide a somegeneous smooth solid surface are considered; evolving drop shapes, what limited picture of contact angle hysteresis. This is so, as a function of incremental changes in their volume, are investisince the cross-section of the drop-shape must be circular gated. Results are presented for a model system in which the (in the absence of gravity or other external forces, and ignorintrinsic contact angle is assumed to vary along the surface in a ing the three-phase interactions at the contact line). This periodic manner. Throughout the simulation, calculated contact fact uniquely determines the contact angle when the position, angles show reasonable agreement with the local intrinsic contact angle values, and the computed drop shapes are found to be con-radius, and volume (per unit depth) are determined. In real stant mean curvature surfaces. Significant hysteresis in the liquidsystems involving three-dimensional sessile drops on solid fluid interface curvature and average contact angle is found; a substrates, there may exist various contact angles along the complete hysteresis loop is simulated. Advancing and receding drop contact line, and the drop may assume a variety of contact angles exhibit the ''stick-slip'' behavior observed in experishapes. ments as well as in previous 2-D simulations.