Effect of contact angle on the orientation, stability, and assembly of dense floating cubes.
Effect of contact angle on the orientation, stability, and assembly of dense floating cubes.
复制标题
接触角对致密浮动立方体的定向、稳定性和组装的影响。
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
J. Rothstein
中科院分区：
文献类型：
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作者：
R. Daniello;Kashan Khan;M. Donnell;J. Rothstein
在本文中，接触角，密度和尺寸的取向，稳定性和浮动立方体组装的影响进行了研究。所有测试的立方体都比水更致密。浮游现象是由于气水界面变形引起的毛细应力而发生的。裸丙烯酸立方体的前进接触角测量为85°。通过用市售超疏水涂料涂覆立方体以达到150°的前进接触角来增加立方体的接触角。根据它们的尺寸、密度和接触角，观察到立方体以三个主要方向之一漂浮：边缘向上、顶点向上和面朝上。建立了一个实验装置，使得重力，浮力和毛细作用力的总和可以使用力传感器作为立方体位置的函数进行测量，因为它是通过空气-水界面降低。测量结果表明，最大的毛细管力总是经历了面向上的方向。然而，当顶点向上方向可以漂浮时，发现它是最稳定的立方体方向，因为它的重心最低。对在三个主要方向中的每一个方向上漂浮的立方体进行一系列理论预测，以计算立方体上的净力。理论预测被发现与实验测量相匹配。从理论预测中得到了立方体取向随接触角和尺寸变化的立方体稳定性图，并发现与实验观察结果吻合得很好。同时，我们还研究了两个、三个和多个立方体的立方体组合体的正面朝上和顶点朝上浮动的立方体组合体。发现面朝上漂浮的立方体面对面地组装并形成规则的正方形晶格图案，立方体之间没有自由界面。顶点向上浮动的立方体被发现以各种不同的排列方式组装，包括边到边、顶点到顶点、面到面和顶点到面，其中最有可能的组装方式是边到边。大量的顶点向上的立方体被发现包装的方向和路线的分布。
In this paper, the effect of contact angle, density, and size on the orientation, stability, and assembly of floating cubes was investigated. All the cubes tested were more dense than water. Floatation occurred as a result of capillary stresses induced by deformation of the air-water interface. The advancing contact angle of the bare acrylic cubes was measured to be 85°. The contact angle of the cubes was increased by painting the cubes with a commercially available superhydrophobic paint to reach an advancing contact angle of 150°. Depending on their size, density, and contact angle, the cubes were observed to float in one of three primary orientations: edge up, vertex up, and face up. An experimental apparatus was built such that the sum of the gravitational force, buoyancy force, and capillary forces could be measured using a force transducer as a function of cube position as it was lowered through the air-water interface. Measurements showed that the maximum capillary forces were always experienced for the face up orientation. However, when floatation was possible in the vertex up orientation, it was found to be the most stable cube orientation because it had the lowest center of gravity. A series of theoretical predictions were performed for the cubes floating in each of the three primary orientations to calculate the net force on the cube. The theoretical predictions were found to match the experimental measurements well. A cube stability diagram of cube orientation as a function of cube contact angle and size was prepared from the predictions of theory and found to match the experimental observations quite well. The assembly of cubes floating face up and vertex up were also studied for assemblies of two, three, and many cubes. Cubes floating face up were found to assemble face-to-face and form regular square lattice patterns with no free interface between cubes. Cubes floating vertex up were found to assemble in a variety of different arrangements including edge-to-edge, vertex-to-vertex, face-to-face, and vertex-to-face with the most probably assembly being edge-to-edge. Large numbers of vertex up cubes were found to pack with a distribution of orientations and alignments.