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叶学民, 姜凯, 沈雷, 李春曦. 含活性剂超薄液膜演化过程的稳定性研究[J]. 力学学报, 2013, 45(5): 681-689. DOI: 10.6052/0459-1879-12-381
引用本文: 叶学民, 姜凯, 沈雷, 李春曦. 含活性剂超薄液膜演化过程的稳定性研究[J]. 力学学报, 2013, 45(5): 681-689. DOI: 10.6052/0459-1879-12-381
Ye Xuemin, Jiang Kai, Shen Lei, Li Chunxi. STABILITY OF ULTRATHIN LIQUID FILM EVOLUTION WITH SURFACTANT[J]. Chinese Journal of Theoretical and Applied Mechanics, 2013, 45(5): 681-689. DOI: 10.6052/0459-1879-12-381
Citation: Ye Xuemin, Jiang Kai, Shen Lei, Li Chunxi. STABILITY OF ULTRATHIN LIQUID FILM EVOLUTION WITH SURFACTANT[J]. Chinese Journal of Theoretical and Applied Mechanics, 2013, 45(5): 681-689. DOI: 10.6052/0459-1879-12-381

含活性剂超薄液膜演化过程的稳定性研究

STABILITY OF ULTRATHIN LIQUID FILM EVOLUTION WITH SURFACTANT

  • 摘要: 针对固体基底上厚度小于100 nm的含活性剂超薄液膜演化过程, 基于润滑理论推导出包含分离压影响的液膜厚度和活性剂浓度的演化方程, 采用正则模态法导出了描述液膜线性稳定性的特征方程, 分析了多个特征参数对线性稳定性的影响, 数值模拟了液膜厚度和活性剂浓度演化历程, 对比了模拟所得非线性结果与线性分析预测结果的一致性.结果表明:范德华力具有促进扰动增长的作用, 较强的玻恩斥力促使扰动衰减, 使液膜趋于稳定;较小的毛细力数易使液膜凹陷处发生二次失稳, 并最终导致去润湿现象发生;液膜厚度和溶于液膜内部的活性剂浓度初值越大, 液膜稳定性越强, 液膜表面活性剂浓度影响则相反;增大吸附系数不利于液膜稳定性.

     

    Abstract: For an ultrathin liquid film thickness less than 100 nm, instability often accompanies ultrathin liquid film flow driven by surfactant on solid substrate. In present paper, the process of film evolution under the effect of disjoining pressure was simulated with three evolution equations for the film thickness, surfactant interfacial and bulk concentration, which are derived in lubrication approximation. The effects of characteristic parameters on the stability of evolution process are analyzed, and the coincidence between the stability prediction based on linear theory and the simulation results with nonlinear characteristic equation derived with regular modules method is compared. Results show that van der Waals forces promote the instability characteristic while Born repulsion depress it; the secondary instability occurs on the depression section of the film under the condition of small capillary number, which results in a dewetting structure formation ultimately; the increasing of initial value of the film thickness and surfactant bulk concentration enhances the stability of film evolution, however, the increasing of interfacial concentration and the adsorption coefficient leads to an opposite effect instead.

     

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