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Schlagwörter:
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Zusammenfassung:
Thin, viscous liquid films subjected to impact events can deform. Here we investigate
free-surface oil-film deformations that arise owing to the build up of air under the
impacting and rebouncing of water drops. Using digital holographic microscopy, we
measure the three-dimensional surface topography of the deformed film immediately after
the drop rebound, with a resolution down to 20 nm.We first discuss how the film is initially
deformed during impact, as a function of film thickness, film viscosity and drop impact
speed. Subsequently, we describe the slow relaxation process of the deformed film after
the rebound. Scaling laws for the broadening of the width and the decay of the amplitude
of the perturbations are obtained experimentally and found to be in excellent agreement
with the results from a lubrication analysis.We finally arrive at a detailed spatio–temporal
description of the oil-film deformations that arise during the impact and rebouncing of
water drops.
