scholarly journals Linear stability analysis of an insoluble surfactant monolayer spreading on a thin liquid film

1997 ◽  
Vol 9 (12) ◽  
pp. 3645-3657 ◽  
Author(s):  
Omar K. Matar ◽  
Sandra M. Troian
Keyword(s):  
Stability Analysis ◽  
Liquid Film ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Thin Liquid Film ◽  
Insoluble Surfactant ◽  
Monolayer Spreading

AC electrohydrodynamic instabilities in thin liquid films

2009 ◽  
Vol 631 ◽  
pp. 255-279 ◽  
Author(s):  
SCOTT A. ROBERTS ◽  
SATISH KUMAR
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Electric Fields ◽  
Linear Stability Analysis ◽  
Floquet Theory ◽  
Thin Liquid Film ◽  
Liquid Films ◽  
Dielectric Films ◽  
High Frequencies ◽  
Ac Electric Fields

When DC electric fields are applied to a thin liquid film, the interface may become unstable and form a series of pillars. In this paper, we apply lubrication theory to examine the possibility of using AC electric fields to exert further control over the size and shape of the pillars. For perfect dielectric films, linear stability analysis shows that the influence of an AC field can be understood by considering an effective DC field. For leaky dielectric films, Floquet theory is applied to carry out the linear stability analysis, and it reveals that high frequencies may be used to inhibit the accumulation of interfacial free charge, leading to a lowering of growth rates and wavenumbers. Nonlinear simulations confirm the results of the linear stability analysis while also uncovering additional mechanisms for tuning overall pillar height and width. The results presented here may be of interest for the controlled creation of surface topographical features in applications such as patterned coatings and microelectronics.

scholarly journals Instabilities at a sheared interface over a liquid laden with soluble surfactant

2021 ◽  
Vol 129 (1) ◽  
Author(s):  
A. Kalogirou ◽  
M. G. Blyth
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Fluid Layer ◽  
Threshold Value ◽  
Long Wavelength ◽  
Budget Analysis ◽  
Insoluble Surfactant ◽  
Bounded Below ◽  
Soluble Surfactant

AbstractThe linear stability of a semi-infinite fluid undergoing a shearing motion over a fluid layer that is laden with soluble surfactant and that is bounded below by a plane wall is investigated under conditions of Stokes flow. While it is known that this configuration is unstable in the presence of an insoluble surfactant, it is shown via a linear stability analysis that surfactant solubility has a stabilising effect on the flow. As the solubility increases, large-wavelength perturbations are stabilised first, leaving open the possibility of mid-wave instability for moderate surfactant solubilities, and the flow is fully stabilised when the solubility exceeds a threshold value. The predictions of the linear stability analysis are supported by an energy budget analysis which is also used to determine the key physical effects responsible for the (de)stabilisation. Asymptotic expansions performed for long-wavelength perturbations turn out to be non-uniform in the insoluble surfactant limit. In keeping with the findings for insoluble surfactant obtained by Pozrikidis & Hill (IMA J Appl Math 76:859–875, 2011), the presence of the wall is found to be a crucial factor in the instability.

Stability of evaporating two-layered liquid film in the presence of surfactant—III. Non-linear stability analysis

1998 ◽  
Vol 53 (15) ◽  
pp. 2839-2857 ◽  
Author(s):  
Vesselin N. Paunov ◽  
Krassimir D. Danov ◽  
Norbert Alleborn ◽  
Hans Raszillier ◽  
Franz Durst
Keyword(s):  
Stability Analysis ◽  
Liquid Film ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Non Linear
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