Natural oscillations of a sessile drop on flat surfaces with mobile contact lines
Natural oscillations of a sessile drop on flat surfaces with mobile contact lines
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DOI：
10.1103/physrevfluids.5.123604
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发表时间：
2020-12-18
影响因子：
2.7
通讯作者：
Ling, Yue
中科院分区：
文献类型：
--
作者：
Sakakeeny, Jordan;Ling, Yue
固着液滴的振荡对许多应用都很重要。本文通过数值计算和理论分析，研究了具有自由接触线（FCL）的平表面上的固着液滴的固有振动。FCL条件表示接触线迁移率的极限，即，当接触线移动时，接触角保持恒定。在数值模拟中，界面由流体体积法捕获，边界处的接触角由高度函数法确定。固着液滴与FCL的振荡频率主要由接触角和键数控制，并进行了参数研究，以表征其对第一和高阶模式的频率的影响。特别注意第一模式的频率，因为它通常是主导模式。建立了第一阶模态的无粘理论模型。该模型产生的第一模式的频率作为接触角和键数的函数，与所有涉及的参数完全由平衡液滴理论和模拟确定的明确的表达式。预测的频率范围广泛的接触角同意非常好的模拟结果为小邦德数。一阶和高阶模的频率都随接触角的增大而减小，随键数的增大而增大。对于高阶模式，不同模式的频率通常与瑞利频率成比例。标度关系对于小的Bond数和大的接触角表现得更好。提出了一个简单的模型来预测高阶模式的频率为大的接触角和一个很好的协议与模拟结果进行了观察。
Oscillation of sessile drops is important to many applications. In the present study, the natural oscillation of a sessile drop on flat surfaces with free contact lines (FCL) is investigated through numerical and theoretical analysis. The FCL condition represents a limit of contact line mobility, i.e., the contact angle remains constant when the contact line moves. In the numerical simulation, the interfaces are captured by the volume-of-fluid method and the contact angle at the boundary is specified using the height-function method. The oscillation frequencies for sessile drops with FCL are mainly controlled by the contact angle and the Bond number and a parametric study is carried out to characterize their effects on the frequencies for the first and high-order modes. Particular attention is paid to the frequency of the first mode, since it is usually the dominant mode. An inviscid theoretical model for the first mode is developed. The model yields an explicit expression for the first-mode frequency as a function of the contact angle and the Bond number, with all parameters involved fully determined by the equilibrium drop theory and the simulation. The predicted frequencies for a wide range of contact angles agree very well with the simulation results for small Bond numbers. The frequencies for both the first and high-order modes decrease with the contact angle and increase with the Bond number. For the high-order modes, the frequencies for different modes generally scale with the Rayleigh frequencies. The scaling relation performs better for small Bond numbers and large contact angles. A simple model is proposed to predict the frequencies of high-order modes for large contact angles and a good agreement with the simulation results is observed.