Spreading Kinetics of Constrained Thin Films

液体在固体表面上扩散的速率称为润湿动力学，它研究的是液体在固体表面上移动并取代第二种流体的速率。由于液膜厚度随着接触线（固-液-气相共同的接触线）的逼近而逐渐减小到零，因此薄液膜的特殊性质起了重要作用。这里重要的是分离压力，它与薄膜（小于100纳米）中的多余电位有关，可以用作描述流体动力学和平衡的体力。本分析研究是针对液体在分离压力中对固体基材既有吸引力又有排斥力的情况，这种情况很常见，但尚未进行分析。虽然薄膜现象决定了液体是不润湿的，但在实验中，扩散动力学本身似乎不受分离压力的影响，直到运动的液体突然达到平衡。对这种行为如何产生的定量描述将从本研究的结果中得到明确。对运动液膜轮廓的流体力学方程进行数值求解。数值方法非常困难，因为需要观察两个非常不同的长度尺度，即基本液体质量的尺度和薄膜尺寸的尺度，并且需要很长时间。此外，还将考虑液体蒸发和表面粗糙度的影响，因为它们给分析带来了很大的现实性。

Parthasakha NeogiU of Missouri - Rolla"Spreading Kinetics of Constrained Thin Films"The rate at which a liquid spreads over a solid surface is called the wetting kinetics, which deals with the rates at which a liquid moves over a solid surface and displaces a second fluid. Since the liquid film thickness gradually decreases to zero as the contact line, the line common to the solid-liquid-vapor phases, is approached, the special properties of thin liquid films play an important role. Of importance here is the disjoining pressure, which is related to the excess potential in thin films (less than 100 nanometers), and can be used as a body force to describe the hydrodynamics and equilibrium. This analytical research is for a liquid that has both attraction and repulsion for the solid substrate in its disjoining pressure, which is common but has not been analyzed. Although the thin film phenomenon determines that the liquid is non-wetting, the dynamics of spreading itself seems unaffected in the experiments by the disjoining pressure until the time when the moving liquid suddenly equilibrates. A quantitative description of how such a behavior arises will be made clear from the results of this research. The fluid mechanical equations for the profile of the moving liquid film will be solved numerically. The numerical method is made very difficult by the need to look at two very different length scales, the scale of the basic liquid mass and the thin film dimensions, and over very long times. Additionally, the effect of liquid evaporation and surface roughness will be considered, since they bring in great deal of reality to the analysis.