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arXiv · 2503.08331

Orbiting, colliding and merging droplets on a soap film: toward gravitational analogues

Jean-Paul Martischang·Benjamin Reichert·Germain Rousseaux·Alexis Duchesne·Michael Baudoin
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Abstract

Modern telescopes provide breathtaking images of nebulae, clouds and galaxies shaped by gravity-driven interactions between complex bodies. While such structures are prevalent on an astrophysical scale, they are rarely observed at the human scale. In this letter, we report the observations of the complex orbits, collision, and coalescence of droplets on a soap film, forming structures such as bridges and spiral arms, reminiscent of their astrophysical counterparts. These dynamics emerge from attractive forces caused by gravito-capillary-driven distortions of the supporting soap film. Long orbits and intricate coalescence mechanisms are enabled by the small dissipation in the soap film and the fluidic nature of the droplets and supporting film, respectively. The existence of stable droplets within the soap film featuring a universal radius, as well as the attractive potentials, are explained through a careful comparison of experimental data with models computing the distortions of the supporting soap film. This work opens perspectives to

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Jean-Paul Martischang, Benjamin Reichert, Germain Rousseaux, Alexis Duchesne, Michael Baudoin. 2025-03-11. Orbiting, colliding and merging droplets on a soap film: toward gravitational analogues. https://arxiv.org/abs/2503.08331

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