Wed February 4th 2009
Seminar Various situations in drop impact problems
Philippe Brunet


The study of drop splashes is a long-standing problem that has been studied extensively since the first systematic experiments by Worthington more than 100 years ago. Some clues suggesting that Leonardo da Vinci drew realistic pictures of splashes in the 16th century - hence, without the help of a high-speed camera - area available in some book (Codex Leicester).

Still, many open questions remains: the difficulties to set-up reproducible experiments, and the large range of length and time scales involved require very accurate experiments. Furthermore, the presence of a rather complex moving interface still challenges the most sophisticated numerical schemes.
One of the questions that still lacks a definite answer, is the mechanism of the formation of the so-called 'Edgerton's crown': a more or less regular pattern of liquid fingers formed after the impact of a drop on a thin layer of the same liquid, and widely popularized in milk or coffee advertisements.
I will present an experimental study that aimed to track the development of the fingering structure, and I will try to show how bad or well it compares with the existing mechanisms. From accurate experimental data, it turns out that the regularity of the crown formation is due to a capillary instability of the toroidal rim that develops at the periphery of the annular sheet, formed just after the impact.

In a second part, I will present a brief account of other drop impact phenomenon, in particular the problem of impact on a superhydrophobic textured surface.
Go back to the agenda.

The 10th Complex Motion in Fluids 2020
Max Planck Gesellschaft
Centre for Scientific Computing