substrate Dynamical Analysis of Droplet Impact Spreading on Solid Substrate

The spray coating process has been introduced as a new, non-contact technique to coat process, which is widely used in thermal spreading [1], spread cooling, ink jet technology, DNA microarrays [2], and other industrial techniques. Although a number of pilot scale trials have been carried out, relatively little is known about the fundamental mechanisms on how to control spray coating. The spray coating process can be divided into droplet formation, droplet impact spreading, consolidation and drying of coating layer, etc. Each sub-process has an influence on the outcome of coating. Therefore, fundamental aspects of each of the sub-processes should be understood if optimal operation of spray coating is to be achieved. The present work focuses on the sub-process of droplet impact spreading. This very short duration event where droplets come in contact with the substrate at high velocities and spread due to the kinetic energy of droplets is currently not well understood [3]. Impact spreading of droplets on the solid substrate is investigated by making use of numerical simulation based on a volume-of-fluid (VOF) model in this paper. The results include the process of droplet spreading, the analysis of the low speed and high speed droplet spreading, and more than one droplet spreading simultaneously. Pressure, velocity an