title: On the shape of giant soap bubbles.
abstract: We study the effect of gravity on giant soap bubbles and show that it becomes dominant above the critical size [Formula: see text], where [Formula: see text] is the mean thickness of the soap film and [Formula: see text] is the capillary length ([Formula: see text] stands for vapor-liquid surface tension, and [Formula: see text] stands for the liquid density). We first show experimentally that large soap bubbles do not retain a spherical shape but flatten when increasing their size. A theoretical model is then developed to account for this effect, predicting the shape based on mechanical equilibrium. In stark contrast to liquid drops, we show that there is no mechanical limit of the height of giant bubble shapes. In practice, the physicochemical constraints imposed by surfactant molecules limit the access to this large asymptotic domain. However, by an exact analogy, it is shown how the giant bubble shapes can be realized by large inflatable structures.
authors.affiliation: Laboratoire d'Hydrodynamique de l'X, UMR 7646 CNRS, École Polytechnique, 91128 Palaiseau Cedex, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Cohen
authors.affiliation: Laboratoire d'Hydrodynamique de l'X, UMR 7646 CNRS, École Polytechnique, 91128 Palaiseau Cedex, France.
authors.forename: Baptiste
authors.initials: B
authors.lastname: Darbois Texier
authors.affiliation: Laboratoire de Physique et Mécanique des Milieux Hétérogènes (PMMH), UMR 7636 du CNRS, ESPCI Paris/Paris Sciences et Lettres (PSL) Research University/Sorbonne Universités/Université Paris Diderot, 75005 Paris, France; etienne.reyssat@espci.fr.
authors.forename: Etienne
authors.initials: E
authors.lastname: Reyssat
authors.affiliation: Physics of Fluids Group, University of Twente, 7500 AE Enschede, The Netherlands.|MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands.|Department of Applied Physics, Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands.
authors.forename: Jacco H
authors.initials: JH
authors.lastname: Snoeijer
authors.affiliation: Laboratoire de Physique et Mécanique des Milieux Hétérogènes (PMMH), UMR 7636 du CNRS, ESPCI Paris/Paris Sciences et Lettres (PSL) Research University/Sorbonne Universités/Université Paris Diderot, 75005 Paris, France.
authors.forename: David
authors.initials: D
authors.lastname: Quéré
authors.affiliation: Laboratoire d'Hydrodynamique de l'X, UMR 7646 CNRS, École Polytechnique, 91128 Palaiseau Cedex, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Clanet
keywords: Marangoni stress; self-similarity; soap bubbles