Instability and dynamics of thin viscoelastic liquid films |
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Authors: | G Tomar V Shankar S K Shukla A Sharma G Biswas |
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Institution: | (1) Department of Mechanical Engineering, Indian Institute of Technology, 208016 Kanpur, India;(2) Department of Chemical Engineering, Indian Institute of Technology, 208016 Kanpur, India |
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Abstract: | The instability, rupture, and subsequent growth of holes in a thin Jeffreys-type viscoelastic film under the influence of
long-range van der Waals force are investigated using both linear stability analysis and nonlinear numerical solutions. The
linear stability analysis of full governing equations valid for arbitrary wave numbers shows that although fluid rheology
does not influence the dominant length scale of the instability, it significantly affects the growth rate. It is shown that
neglect of inertia and solvent dynamics results in a nonphysical singularity in the growth rate beyond a critical value of
relaxation time. We further carry out numerical simulations of a set of long-wave, nonlinear differential equations (also
derived in Rauscher et al., Eur. Phys. J. E 17, 373 (2005)) governing the evolution of the free surface. The nonlinear simulations, in their domain of validity, confirm
the results of the linear analysis. Interestingly, results from nonlinear simulations further show that both for Newtonian
and viscoelastic liquids, the shape and the dewetting dynamics of a hole are identical when examined in terms of a rescaled
time which depends on rheological parameters. Thus, viscoelasticity of Jeffreys type merely accelerates the growth rate, without
however affecting the important morphological characteristics. |
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Keywords: | 68 15 +e Liquid thin films 47 50 -d Non-Newtonian fluid flows 47 15 gm Thin film flows 47 55 dr Interactions with surfaces |
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