Damping of Thermocapillary Destabilization of a Liquid Film in Zero Gravity Through the Use of an Isothermal Porous Substrate

Aneet Dharmavaram Narendranath

Abstract


Thin liquid films on isothermal substrates, where the film is flat and parallel to the substrate, succumb to thermocapillary instabilities and rupture, forming local hot-spots. These long wavelength instabilities are specific to aspect ratios where the liquid film mean thickness is several orders of magnitude less than the substrate characteristic dimension. Absent stabilizing gravitational acceleration, the growth rate of thermocapillary instabilities is further intensified, driving the film to rupture even earlier.
Numerical simulations of zero gravity dynamics of Newtonian liquid films on a solid, horizontal, isothermal substrate were conducted. When the solid, isothermal substrate was replaced with a one-dimensionally porous substrate, was fully saturated with the same fluid as the liquid film, and was deep enough to accommodate all the liquid on it, we observed that destabilizing spatial modes were damped thereby preventing rupture and prolonging the film lifespan. This nonlinear evolution was visualized and quantified using recurrence plots.

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