Abstract
This work is first devoted to the suspension or collapse study of water droplet on rough surface based on the equilibrium of force using Surface Evolver program. The results are compared with the experiment by Extrand (2002). Then, taking similar convex epidermal cells of lotus as rough surface, different sizes of suspended water droplets (with diameter between ) are analyzed for calculating their maximum height and diameter. The results show that, when the diameter of water droplets is from to, more distinct influence of gravity on the maximum height of water droplets will be found as the diameter gets larger, but the effect on the maximum diameter can be ignored. However, when the diameter of water droplets is smaller than, the gravity effect is negligible compared with that of surface tension. This work also focuses on the study of the coalescence of two water droplets on different smooth surfaces. The mistake of experiment data made by Narhe et al.(2004) is corrected. The coalescence of two droplets with different surface tensions on smooth surface is also explored. The results achieved in this work will be helpful for the relevant researches of nano/micro technology and biotechnology.