Effect of interfacial phenomena on dewetting in dropwise condensation.

Image-analyzing interferometry was used to investigate the dynamics of the dewetting meniscus of a partially wetting fluid on a modified quartz surface during dropwise condensation. The vivid difference in the behavior of the retracting meniscus with respect to its variation in apparent contact angle and curvature after the merger of the drop with the meniscus was found to depend on the wettability of the surface. On the hydroxylated quartz surface, the meniscus shed mass during retraction. The dewetting velocity decreased with time. On a slightly hydrophobic quartz surface, the meniscus showed a curvature gradient in the axial direction during drop merger and that gradient decreased as the meniscus moved towards the corner. The dewetting of the meniscus is discussed using the interfacial concepts of spreading and the Kelvin-Clapeyron phase change model.