Formation of Precursor Film Ahead Macroscopic Contact Line of Spreading Droplet
Ichiro Ueno, Yoshiaki Kisara, Kanji Hirose and Yusuke Kizaki
There exits a wafer-thin liquid film ahead the macroscopic contact line of the droplet spreading on a substrate in rather complete wetting system. This thin film is called as ‘precursor film.’ Preceding studies have indicated its existing length and profile in the case of fully developed state. We focus on a transition growth process of the precursor film at an early stage of the droplet spreading. We employ a Brewster-angle microscopy as well as a conventional laser interferometry in order to detect spatio- temporal process of the precursor film formation. We indicate the growth process of the precursor film and make a comparison with theoretical and experimental studies on ‘adiabatic’ precursor film.
Keywords: Precursor film, Brewster-angle microscopy, interferometer, spreading, droplet, macroscopic contact line.