In hydrophobic mini- and microchannels, slug flow with moving contact lines is typically generated under various two-phase flow conditions. There is a significant pressure drop in this flow pattern with moving contact lines, which is closely related to the dynamic contact angles. Researchers have investigated dynamic contact angles experimentally for decades, but due to the limitations of visualization techniques, these experiments have typically been conducted in low Weber number regions (We < 10^–3). In this study, we clearly visualized the dynamic contact angles of a liquid slug in high Weber number regions (10^–3 < We <1) via synchrotron X-ray imaging with high temporal (∼1000 fps) and spatial (∼2 μm/pixel) resolutions. We precisely measured the pressure drop with moving contact lines in a hydrophobic minichannel (inner diameter = 1.018 mm). On the basis of our experimental data, we verified previous correlations for dynamic contact angles and explored the relationship between pressure drop with moving contact lines and dynamic contact angles.

中文翻译：

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疏水圆形微型通道中具有移动接触线和动态接触角的压降：通过同步加速器X射线成像可视化并验证实验相关性。

在疏水性微通道和微通道中，通常在各种两相流条件下产生带有活动接触线的团状流。随着接触线的移动，在这种流动模式中存在明显的压降，这与动态接触角密切相关。研究人员已经通过实验研究了动态接触角数十年，但是由于可视化技术的局限性，这些实验通常是在低韦伯数区域（We <10 ^–3）进行的。在这项研究中，我们清楚地看到了高Weber数区域（10 ^–3 < We<1）通过具有高时间分辨率（〜1000 fps）和空间分辨率（〜2μm/像素）的同步加速器X射线成像。我们在疏水性微型通道（内径= 1.018 mm）中通过移动接触线精确测量了压降。根据我们的实验数据，我们验证了先前动态接触角的相关性，并探讨了运动接触线的压降与动态接触角之间的关系。