Ramé E
Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania, 15213
J Colloid Interface Sci. 1997 Jan 1;185(1):245-51. doi: 10.1006/jcis.1996.4589.
We present an analysis for properly interpreting apparent dynamic contact angles measured using the Wilhelmy plate method at low capillary numbers, Ca. This analysis removes the ambiguity in current dynamic measurements which interpret data with the same formula as static measurements. We properly account for all forces, including viscous forces, acting on the plate as it moves into or out of a liquid bath. Our main result, valid at O(1) as Ca --> 0, relates the apparent dynamic contact angle to material-dependent, geometry-independent parameters necessary for describing dynamic wetting of a system. The special case of the apparent contact angle = pi/2 was solved to O(Ca). This O(Ca) solution can guide numerical work necessary for higher Ca's and arbitrary values of the apparent contact angle. These results make the Wilhelmy plate a viable method for determining material parameters for dynamic spreading.
我们给出了一种分析方法，用于正确解释在低毛细管数Ca下使用Wilhelmy板法测量的表观动态接触角。该分析消除了当前动态测量中的模糊性，当前动态测量使用与静态测量相同的公式来解释数据。当板移入或移出液池时，我们正确地考虑了作用在板上的所有力，包括粘性力。我们的主要结果在Ca→0时在O(1)量级有效，它将表观动态接触角与描述系统动态润湿性所需的与材料相关、与几何无关的参数联系起来。表观接触角=π/2的特殊情况被求解到O(Ca)量级。这个O(Ca)量级的解可以指导对于更高Ca值和任意表观接触角值所需的数值工作。这些结果使得Wilhelmy板成为确定动态铺展材料参数的一种可行方法。
