报告题目：  

Numerical study of drop motion on a surface with stepwise wettability gradient and  

contact angle hysteresis 

报告人:                          黄军杰   副教授  

重庆大学工程力学系  

时间：2014年8月25日(周一)   16:00-17:00                                                       

地点：中国科学院力学研究所主楼344会议室  

报告摘要：  

To drive and control the motion of discrete drops through modifications of surface wettability possesses many advantages at small scales. Such problems have received growing attention because of their significance in the development of lab-on-a-chip technologies. In this work, the motion of a two-dimensional drop on a surface with stepwise 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 series of tests that check different constituents of the numerical model. Then, simulations of a drop on a wall with given stepwise 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 was discovered that the shape of the drop in steady motion may be fitted by two arcs that give two apparent contact angles, which are related to the respective contact line velocities and the relevant contact angles (that specify the WG and CAH) through the relation derived by Cox [“The dynamics of the spreading of liquids on a solid surface. Part 1. viscous flow,”  –194 (1986)] if the slip length in simulation is defined according to Yue et al. [“Sharp-interface limit of the Cahn-Hilliard model for moving contact lines,”  –294 (2010)]. It was also found that the steady capillary number of the drop is significantly affected by the viscosity ratio, the magnitudes of the WG, and the CAH, whereas it almost shows no dependence on the Reynolds number.  J. Fluid Mech. 645, 279J. Fluid Mech. 168, 169

报告人简介：  

黄军杰，重庆大学工程力学系副教授。2002年清华大学工程力学系毕业，2010年获新加坡国立大学机械工程博士，2007-2011年于新加坡国立大学淡马锡研究所（Temasek Laboratories）从事计算空气动力学方面的工作，先后任Associate Scientist及Research Scientist，2011年至今任重庆大学副教授。主要研究方向为格子Boltzmann方法、基于相场的多相流模拟及浸润等，已在包括Journal of Colloid and Interface Science、Physics of Fluids等期刊上发表十多篇论文（第一作者8篇）。研究工作获国家自然科学基金、重庆市自然科学基金等资助。曾担任国家自然科学基金项目通讯评审及Journal of Colloid and Interface Science、International Journal of Heat and Mass Transfer、International Journal for Numerical Methods in Fluids等期刊审稿人。