A simple analytic model for predicting the wicking velocity in micropillar arrays
A simple analytic model for predicting the wicking velocity in micropillar arrays
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DOI：
10.1038/s41598-019-56361-7
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发表时间：
2019-12-27
影响因子：
4.6
通讯作者：
Putnam, Shawn A.
中科院分区：
文献类型：
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作者：
Krishnan, Siva Rama;Bal, John;Putnam, Shawn A.
半芯吸是液体由于毛细作用和吸胀而润湿纹理化表面超过其固有润湿长度的现象。在这项工作中，我们推导出一个简单的分析模型半芯吸微柱阵列。该模型基于由弯曲的液体弯月面内的界面和分子间压力梯度以及在超低雷诺数（10（-7）小于或类似于小于或类似于10（-3）的Re）下来自柱的流体阻力决定的毛细管作用的组合效应。流体阻力通过临界雷诺数来概念化：Re = v（0）x（0）/nu，其中v（0）对应于平坦干燥表面上的最大润湿速度，x（0）是液体弯月面的延伸长度，该延伸长度将本体流体驱动到吸附的薄膜区域。该模型通过在不同半芯吸表面上的芯吸实验结合使用水（v（0）约为2 m/s，25 μ m小于或类似于x（0）小于或类似于28 μ m）、粘性FC-70（v（0）约为0.3m/s，18.6 μ m小于或类似于x（0）小于或类似于38.6 μ m）和较低粘度乙醇（v（0）近似于1.2 m/s，11.8 μ m小于或类似于x（0）小于或类似于33.3 μ m）。
Hemiwicking is the phenomena where a liquid wets a textured surface beyond its intrinsic wetting length due to capillary action and imbibition. In this work, we derive a simple analytical model for hemiwicking in micropillar arrays. The model is based on the combined effects of capillary action dictated by interfacial and intermolecular pressures gradients within the curved liquid meniscus and fluid drag from the pillars at ultra-low Reynolds numbers (10(-7) less than or similar to Re less than or similar to 10(-3)). Fluid drag is conceptualized via a critical Reynolds number: Re = v(0)x(0)/nu, where v(0) corresponds to the maximum wetting speed on a flat, dry surface and x(0) is the extension length of the liquid meniscus that drives the bulk fluid toward the adsorbed thin-film region. The model is validated with wicking experiments on different hemiwicking surfaces in conjunction with v(0) and x(0) measurements using Water (v(0) approximate to 2 m/s, 25 mu m less than or similar to x(0) less than or similar to 28 mu m), viscous FC-70 (v(0) approximate to 0.3 m/s, 18.6 mu m less than or similar to x(0) less than or similar to 38.6 mu m) and lower viscosity Ethanol (v(0) approximate to 1.2 m/s, 11.8 mu m less than or similar to x(0) less than or similar to 33.3 mu m).