Numerical study of droplet impact and coalescence in a microline patterning process

The droplet impact and coalescence on a substrate, which is applicable to the manufacture of microlines, is studied numerically by solving the equations governing the conservation of mass and momentum. The liquid–gas interface or droplet shape is tracked by a sharp-interface level-set method which is modified to account for the change between advancing and receding contact angles at the liquid–gas–solid interline. The numerical results show that the droplet impact and merging pattern depends significantly on the advancing and receding contact angles. Also, the effect of droplet spacing on the droplet motion is investigated to find the optimal conditions in manufacturing microlines.