Oscillation characteristics of droplets on solid surfaces with air flow

Visual experiments were conducted to observe droplet oscillation on horizontal surfaces with air flow. The different Cu test surfaces were polished with different grit sandpapers. Two liquid drop oscillation modes, forward-backward and upward-downward, were visually observed in the experiments. Additionally these two modes were observed to transition from one to another under some conditions. The results indicate that the oscillating characteristics were closely dependent on surface roundness, droplet size, and air flow velocity. A larger radius and higher air speed would decrease the oscillation frequency, while the frequency would initially decrease and then increase as the roughness changed from the smooth to rough plates. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(1): 13–19, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20098