Thin-film coating of surfactant-laden liquids on rotating cylinders
Thin-film coating of surfactant-laden liquids on rotating cylinders
复制标题
旋转圆筒上负载表面活性剂的液体的薄膜涂层
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
Satish Kumar
中科院分区：
文献类型：
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作者：
Weihua Li;Satish Kumar
出于提高对离散物体涂层的基本认识的需要，在这项工作中考虑了表面活性剂对旋转圆柱体周围的薄液膜流动的影响。润滑近似推导出三个耦合的非线性演化方程描述的变化的膜厚度，表面活性剂的表面浓度，表面活性剂的体积浓度作为时间和角坐标的函数。在没有重力效应的情况下，线性稳定性分析表明，Marangoni应力抑制由离心力驱动的不稳定性的增长率，并阻碍对膜厚度的扰动的平整。当存在重力效应时，马兰戈尼应力降低了引起液体圆瓣围绕圆柱体运动所需的临界转速。这些应力也会在相对较短的时间内导致膜厚振荡的更快衰减，但如果足够强，它会增加振荡。
Motivated by the need to improve fundamental understanding of the coating of discrete objects, the influence of surfactants on the flow of thin liquid films around rotating cylinders is considered in this work. The lubrication approximation is applied to derive three coupled nonlinear evolution equations describing the variation of the film thickness, surfactant surface concentration, and surfactant bulk concentration as a function of time and the angular coordinate. In the absence of gravitational effects, linear stability analysis reveals that Marangoni stresses suppress the growth rate of instabilities driven by centrifugal forces and hinder the leveling of perturbations to the film thickness. When gravitational effects are present, Marangoni stresses lower the critical rotation rate needed to cause motion of a liquid lobe around the cylinder. These stresses also lead to faster damping of oscillations in the film thickness at relatively short times, but if strong enough, it can increase the oscillation...