Semprebon Ciro, Brinkmann Martin
Department Dynamics of Complex Fluids, Max-Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, D-37077 Göttingen, Germany.
Soft Matter. 2014 May 14;10(18):3325-34. doi: 10.1039/c3sm51959g. Epub 2014 Mar 18.
In this article we numerically investigate the onset of motion of liquid drops in contact with a plane and homogeneous substrate with contact angle hysteresis. The drops are driven by a body force F = ρgV, where ρ is the density of the liquid, g is the acceleration of gravity, and V is the volume of the drop. We compare two protocols to vary the bond number Bo = λ(v)/λ(c) by changes of either the drop size λ(v) = V(1/3) or the capillary length λ(c) = (γ/ρg)(1/2) where γ is the interfacial tension, revealing that the transition between pinned and steady moving states can be either continuous or discontinuous. In a certain range both pinned and moving states can be found for a given bond number Bo, depending on the history of the control parameters g and V. Our calculations are extended to arbitrary combinations of static advancing and receding contact angles and provide a comprehensive picture of the depinning transition induced by a quasi-static variation of the control parameters. Finally, we demonstrate that the particular form of the contact line mobility in our model has an impact on the interfacial shape of steady moving drops.
在本文中，我们通过数值方法研究了与具有接触角滞后的平面均匀基底接触的液滴的运动起始情况。液滴由体力F = ρgV驱动，其中ρ是液体的密度，g是重力加速度，V是液滴的体积。我们比较了两种通过改变液滴尺寸λ(v) = V(1/3)或毛细长度λ(c) = (γ/ρg)(1/2)（其中γ是界面张力）来改变键数Bo = λ(v)/λ(c)的方案，结果表明固定状态和稳定移动状态之间的转变可以是连续的，也可以是不连续的。在一定范围内，对于给定的键数Bo，根据控制参数g和V的历史情况，可以找到固定状态和移动状态。我们的计算扩展到了静态前进和后退接触角的任意组合，并为准静态变化的控制参数引起的脱钉转变提供了全面的描述。最后，我们证明了我们模型中接触线迁移率的特定形式对稳定移动液滴的界面形状有影响。
