Asymptotic theory of fluid entrainment in dip coating
Asymptotic theory of fluid entrainment in dip coating
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浸涂中流体夹带的渐近理论
DOI：
10.1017/jfm.2018.224
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发表时间：
2018-04-16
影响因子：
3.7
通讯作者：
Gao, Peng
中科院分区：
文献类型：
--
作者：
Qin, Jian;Gao, Peng
当接触线以足够大的速度移动时，根据接触线移动的方向，液体或气体膜可以被夹带在固体上。在这项工作中，接触线动力学的情况下，一个通用的两个流体系统进行了研究。我们证明了接触线的流体动力学，无论是前进或后退，可以正式减少到一个小的界面斜率后退。由于后者可以很好地处理下的经典润滑近似，这个类比使我们能够推导出一个渐近解的界面轮廓的任意值的接触角和粘度比。对于浸涂的几何形状，我们得到，没有可调参数，润湿过渡的临界速度的分析公式，特别是预测液体和气体夹带的发病。此外，本分析还建立了一个新的连接之间的Cox-Voinov定律和经典的润滑理论的移动接触线。
When a contact line moves with a sufficiently large speed, liquid or gas films can be entrained on a solid depending on the direction of contact-line movement. In this work, the contact-line dynamics in the situation of a generic two-fluid system is investigated. We demonstrate that the hydrodynamics of a contact line, no matter whether advancing or receding, can formally reduce to that of a receding one with small interfacial slopes. Since the latter can be well treated under the classical lubrication approximation, this analogy allows us to derive an asymptotic solution of the interfacial profiles for arbitrary values of contact angle and viscosity ratio. For the dip-coating geometry, we obtain, with no adjustable parameters, an analytical formula for the critical speed of wetting transition, which in particular predicts the onset of both liquid and gas entrainment. Moreover, the present analysis also builds a novel connection between the Cox–Voinov law and classical lubrication theory for moving contact lines.