Detection of advancing edge and length of precursor film ahead of macroscopic contact line of droplet spreading on solid substrate.
The authors carried out an experimental study with a special interest on the dynamics of the fluid near the boundary line of three phases: solid-liquid-gas interface. A spreading droplet on a solid substrate is accompanied by the movement of a visible boundary line called the macroscopic contact line. Previous studies by various research groups have indicated the existence of a thin liquid film known as a precursor film ahead of the macroscopic contact line of the droplet. The present authors focused on the early stage of spreading and dedicated their special effort to detect the advancing edge of the precursor film by applying an interferometer with a high-speed camera and by noise cancellation of using time-frequency analysis of brightness variation. The authors estimated the precursor film length for comparison with theoretical predictions and investigated the effect of changing viscosity on the formation of the precursor film by using the method of detection described herein.
Division of Mechanical Engineering, School of Science and Technology, Tokyo University of Science, Chiba, Japan.
Takumi
T
Konisho
Ichiro
I
Ueno