论文标题
使用移动步骤在基板上转向液滴以润湿性
Steering droplets on substrates using moving steps in wettability
论文作者
论文摘要
液滴以时空的润湿性模式（例如在可轻便的表面上）上的时空润湿性模式移动。为了研究这种情况，我们实施了边界元素方法来解决液滴内部和表面上流体流场的管理方程，并通过Cox-Voinov法律对其进行补充，以进行接触线的动力学。我们的方法重现了实验中轴对称液滴的松弛，我们通过即时切换通过平衡接触角量化的底物的均匀润湿性来启动。在润湿性的步骤中，液滴朝着更高的润湿性移动。使用反馈回路以保持步骤和液滴中心恒定之间的距离或偏移，从而诱导恒定速度，液滴在润湿性步骤上浮出水面。我们分析了典型润湿参数的液滴偏移和步长方面的速度。取而代之的是以恒定的速度移动润湿性步骤，我们在各种条件下确定最大可能的液滴速度。观察到的液滴速度与反馈研究中相同的液滴偏移的值一致。
Droplets move on substrates with a spatio-temporal wettability pattern as generated, for example, on light-switchable surfaces. To study such cases, we implement the boundary-element method to solve the governing Stokes equations for the fluid flow field inside and on the surface of a droplet and supplement it by the Cox-Voinov law for the dynamics of the contact line. Our approach reproduces the relaxation of an axisymmetric droplet in experiments, which we initiate by instantaneously switching the uniform wettability of a substrate quantified by the equilibrium contact angle. In a step profile of wettability the droplet moves towards higher wettability. Using a feedback loop to keep the distance or offset between step and droplet center constant, induces a constant velocity with which the droplet surfes on the wettability step. We analyze the velocity in terms of droplet offset and step width for typical wetting parameters. Moving instead the wettability step with constant speed, we determine the maximally possible droplet velocities under various conditions. The observed droplet speeds agree with the values from the feedback study for the same positive droplet offset.
