Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta T6G 2G8, Canada.
Centro de Investigación en Tecnologías Gráficas, Universitat Politècnica de València, Valencia, Spain.
Adv Colloid Interface Sci. 2014 Jan;203:22-36. doi: 10.1016/j.cis.2013.11.006. Epub 2013 Nov 18.
The diffuse literature on drop oscillation is reviewed, with an emphasis on capillary wave oscillations of constrained drops. Based on the review, a unifying conceptual framework is presented for drop and bubble oscillations, which considers free and constrained drops/bubbles, oscillation of the surface or the bulk (i.e. center of mass) of the drop/bubble, as well as different types of restoring forces (surface tension, gravity, electromagnetic, etc). Experimental results (both from literature and from a new set of experiments studying sessile drops in cross flowing air) are used to test mathematical models from literature, using a novel whole profile analysis technique for the new experiments. The cause of oscillation (cross flowing air, vibrated surface, etc.) is seen not to affect oscillation frequency. In terms of models, simplified models are seen to poorly predict oscillation frequencies. The most advanced literature models are found to be relatively accurate at predicting frequency. However it is seen that no existing models are reliably accurate across a wide range of contact angles, indicating the need for advanced models/empirical relations especially for drops undergoing the lowest frequency mode of oscillation (the order 1 degree 1 non-axisymmetric 'bending' mode that corresponds to a lateral 'rocking' motion of the drop).
对液滴振荡的广泛文献进行了回顾，重点介绍了受约束液滴的毛细波振荡。基于综述，提出了一个统一的液滴和气泡振荡的概念框架，该框架考虑了自由和受约束的液滴/气泡、液滴/气泡表面或体（即质心）的振荡，以及不同类型的恢复力（表面张力、重力、电磁力等）。实验结果（既有文献中的结果，也有一组新的研究横向流空气中固着液滴的实验结果）用于测试文献中的数学模型，对新实验使用了一种新的整体轮廓分析技术。振荡的原因（横向流动的空气、振动的表面等）并不影响振荡频率。就模型而言，简化模型被发现很难预测振荡频率。最先进的文献模型被发现相对准确地预测频率。然而，发现没有现有的模型能够在广泛的接触角范围内可靠地准确预测，这表明需要先进的模型/经验关系，特别是对于经历最低频率振荡模式（即阶数为 1 度 1 的非轴对称“弯曲”模式，对应于液滴的横向“摇摆”运动）的液滴。
