Université Paris-Saclay (Espace Technologique, Bat. Discovery - RD 128 - 2e ét., 91190 Saint-Aubin - France)
Abstract : We study the dynamics of evaporating ethanol films deposited by a receding liquid
meniscus. The films are surrounded by pure vapor in a capillary heated above the saturation
temperature. We observe the substrate dewetting with the dewetting ridge in spite of the
complete wetting at equilibrium. The dewetting is caused by a high contact angle (∼30◦)
induced by evaporation. The obtained values agree with a theory proposed earlier. The film
shape is measured with both grid deflection technique and interferometry. The phenomenon
is convenient to observe inside a capillary with an axial thermal gradient. When the capillary
is closed at one end and open at another to a constant pressure reservoir, the meniscus
oscillations are known to appear spontaneously. Such a system is the simplest version of
an industrial device called a pulsating heat pipe. The effect is general and can be used in
any system to control the wetting properties
L. Fourgeaud, E. Ercolani, J. Duplat, P. Gully, Vadim S. Nikolayev. Evaporation-driven dewetting of a liquid film. Physical Review Fluids, American Physical Society, 2016, 1, pp.41901(R). ⟨10.1103/PhysRevFluids.1.041901⟩. ⟨cea-01485388⟩