AVS 53rd International Symposium
    Surface Science Thursday Sessions
       Session SS-ThP

Paper SS-ThP27
Observation of Internal Fluidity in a Water Droplet during Sliding on Hydrophobic Surfaces by Particle Image Velocimetry

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: Surface Science Poster Session
Presenter: M. Sakai, Kanagawa Academy of Science and Technology, Japan
Authors: M. Sakai, Kanagawa Academy of Science and Technology, Japan
A. Hashimoto, Kanagawa Academy of Science and Technology, Japan
M. Sugibuchi, Kanagawa Academy of Science and Technology, Japan
S. Suzuki, Tokyo Institute of Technology and KAST, Japan
N. Yoshida, CCR, the University of Tokyo and KAST, Japan
Y. Kameshima, Tokyo Institute of Technology and KAST, Japan
A. Nakajima, Tokyo Institute of Technology and KAST, Japan
Correspondent: Click to Email
Recently, the importance of dynamic hydrophobicity (sliding acceleration) is recognized in various industries. In the current paper, we evaluated the sliding behavior; acceleration, advancing-receding contact angles, and the shape of water droplets on various declined hydrophobic surfaces by a high-speed camera system with motion picture analysis. The intensity of the interaction between the solid surface and liquid dominated the sliding behavior of the water droplet. Moreover, during the droplet sliding on the hydrophobic surface, the rolling like a catapillar motion and the slipping on the contact line was observed from the motion of the indicator particle in the droplet. The sliding velocity in the water droplet can be described by the two elements. The cross-section images, which were obtained by a sheet laser (wave length: 488 nm), from the center of the droplet were precisely analyzed by the particle image velocimetry. We successfully confirmed the thickness of boundary layer for the hydrophobic surface by this method. We will discuss the effect of the velocity gradient around the boundary between liquid and the hydrophobic surface on the sliding behavior of water droplets.