Dr Jun-Jie Huang, Numerical Study of Drop Motion on a Surface with Wettability Gradient and Contact Angle Hysteresis
Date: Mon 22 Jul 2013, 11:00 - 12:00
Location: SEMS Seminar Room (3rd Floor Engineering)
Numerical Study of Drop Motion on a Surface with Wettability Gradient and Contact Angle Hysteresis
Dr Jun-Jie Huang
Department of Engineering Mechanics
Drop actuation and transport are essential in digital microfluidics. In this work, the motion of a 2-D drop on a surface with given wettability gradient (WG) is studied numerically by a hybrid lattice-Boltzmann finite-difference method. We incorporate the geometric wetting boundary condition that allows accurate implementation of a contact angle hysteresis (CAH) model. The method is first validated through a few benchmark tests, including the motion of a liquid column in a channel with specified WG and the force balance for a static drop attached to a surface with CAH subject to a body force. Then, simulations of a drop on a wall with given WG are performed under different conditions. The effects of the Reynolds number, the viscosity ratio, the WG, as well as the CAH, on the drop motion are investigated in detail. It is found that the capillary number of the drop in steady state is significantly affected by the viscosity ratio, the magnitudes of the WG and the CAH, whereas it only shows very weak dependence on the Reynolds number.
Jun-Jie Huang is an Associate Professor at the Department of Engineering Mechanics,Chongqing University in Chongqing, China. He obtained his Ph.D. in Mechanical Engineering from the National University of Singapore (NUS) in Singapore, and his bachelor's degree from Tsinghua University in Beijing, China. From 2007-2011, he worked on computational aerodynamics as an Associate Scientist and Research Scientist at Temasek Laboratories, NUS. His current research is mainly on phase-field-based simulations, wetting and the lattice-Boltzmann method. His work is supported by the National Natural Science Foundation of China. He can be reached at email@example.com