Department of Energy, Politecnico di Milano, Via Lambruschini 4, 20156 Milan, Italy.
J Colloid Interface Sci. 2011 Dec 1;364(1):230-6. doi: 10.1016/j.jcis.2011.08.019. Epub 2011 Aug 16.
The shape and contact angles of drops on curved surfaces is experimentally investigated. Image processing, spline fitting and numerical integration are used to extract the drop contour in a number of cross-sections. The three-dimensional surfaces which describe the surface-air and drop-air interfaces can be visualized and a simple procedure to determine the equilibrium contact angle starting from measurements on curved surfaces is proposed. Contact angles on flat surfaces serve as a reference term and a procedure to measure them is proposed. Such procedure is not as accurate as the axisymmetric drop shape analysis algorithms, but it has the advantage of requiring only a side view of the drop-surface couple and no further information. It can therefore be used also for fluids with unknown surface tension and there is no need to measure the drop volume. Examples of application of the proposed techniques for distilled water drops on gemstones confirm that they can be useful for drop shape analysis and contact angle measurement on three-dimensional sculptured surfaces.
我们对曲面液滴的形状和接触角进行了实验研究。通过图像处理、样条拟合和数值积分，从多个横截面中提取液滴轮廓。可以可视化描述表面-空气和液滴-空气界面的三维曲面，并提出了一种从曲面测量开始确定平衡接触角的简单方法。在平面上测量接触角作为参考，并提出了一种测量方法。这种方法不如轴对称液滴形状分析算法准确，但它的优点是只需要液滴-表面对的侧视图，而不需要其他信息。因此，它也可以用于表面张力未知的流体，而且不需要测量液滴体积。对宝石上蒸馏水液滴应用所提出技术的实例证实，它们可用于三维雕刻表面的液滴形状分析和接触角测量。
