Dynamic flotation conditions for elongated cylinders on liquid surfaces
Dynamic flotation conditions for elongated cylinders on liquid surfaces
复制标题
液体表面细长圆柱体的动态浮选条件
DOI：
10.1016/j.jcis.2019.03.091
复制
发表时间：
2019
影响因子：
9.9
通讯作者：
Yao Qiang
中科院分区：
文献类型：
--
作者：
Ji Bingqiang;Tang Zuozhou;Song Qiang;Ge Zhong;Yao Qiang
虽然细长圆柱体的静态浮选已有了较好的认识，但其在接触液体表面后的动态浮选行为，如在水上行走的昆虫所经历的情况，仍然需要揭示。方法考虑细长水平圆柱体与液体表面零速度接触后的运动，建立并求解圆柱体的运动方程，得到动态浮选条件。结果表明，虽然疏水性的增加提高了细长圆柱体的可浮性，但对接触角>；120°影响不大。在能量平衡的基础上，给出了极限密度比的渐近公式，与理论结果吻合较好。与小球体不同，所有接触角为>；0°的细长圆柱体在与液体表面接触后都表现出可漂浮性。此外，我们还发现，与相同接触角和键数的亲水小球相比，加长的亲水圆柱体表现出更好的可浮性，有助于小昆虫在不同的水环境中漂浮和生存。
HypothesisAlthough the static flotation of elongated cylinders is well understood, their flotation behavior under dynamic conditions after contacting a liquid surface, such as in situations experienced by water-walking insects, still need to be revealed.MethodologyThe motion of elongated horizontal cylinders after zero-velocity contact with a liquid surface is considered, and the motion equation of the cylinder is established and solved to obtain the dynamic flotation conditions.FindingsThe limiting density ratios for the dynamic flotation of elongated cylinders with different Bond numbers and contact angles are determined. The results show that although increasing the hydrophobicity promotes floatability of the elongated cylinders, there is little effect for contact angles >120°. Based on the energy balance, an asymptotic formula for the limiting density ratio is proposed, which agrees well with the theoretical results. Unlike small spheres, all elongated cylinders with contact angles >0° are observed to exhibit floatability after contacting a liquid surface. In addition, we found that elongated hydrophilic cylinders exhibit better floatability compared to small hydrophilic spheres with the same contact angle and Bond number, which assists small insects float and survive in various water environments.