We employ high-speed visualization to quantify the impact and evaporation of a droplet on a solid surface. The time-varying droplet shapes are recorded using a high-speed camera and an image processing method is developed for measurement for droplet dimensions, dynamic contact angle, and volume. The method is based on the liquid-gas and liquid-solid interface detection using Canny’s method and Otsu’s method for threshold digitalization. To obtain the dynamic contact angle, a higher-order polynomial is fitted along the pixels near the contact line. The droplet volume is measured assuming an axisymmetric geometry of the droplet and numerically integrating the identified pixels in the droplet. We demonstrate the detection of the complex topology of the deforming liquid-gas interface of an impacting and evaporating droplet on a solid surface. We plot the time-variation of droplet dimensions, namely, wetted diameter, maximum diameter, height; dynamic contact angle, and droplet volume. The contact angle and volume measurements are verified with known analytical values. Three case studies are considered to demonstrate the capability of the proposed method, namely, sessile evaporating droplet, bouncing droplet, and spreading viscous droplet on a solid surface.

我们采用高速可视化技术来量化液滴在固体表面上的撞击和蒸发。使用高速相机记录时变的液滴形状，并开发出图像处理方法来测量液滴尺寸，动态接触角和体积。该方法基于使用Canny方法和Otsu方法进行阈值数字化的液-气和液-固界面检测。为了获得动态接触角，沿着接触线附近的像素拟合高阶多项式。假设液滴的轴对称几何形状并在液滴中对识别出的像素进行数字积分，以测量液滴体积。我们证明了固体表面上撞击和蒸发液滴的变形液-气界面的复杂拓扑结构的检测。我们绘制了液滴尺寸随时间的变化，即湿直径，最大直径，高度；动态接触角和液滴体积。接触角和体积测量值通过已知的分析值进行验证。考虑了三个案例研究，以证明所提出方法的功能，即固着蒸发液滴，弹跳液滴和将粘性液滴散布在固体表面上。