Cohen Caroline, Darbois Texier Baptiste, Reyssat Etienne, Snoeijer Jacco H, Quéré David, Clanet Christophe
Laboratoire d'Hydrodynamique de l'X, UMR 7646 CNRS, École Polytechnique, 91128 Palaiseau Cedex, France.
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;
Proc Natl Acad Sci U S A. 2017 Mar 7;114(10):2515-2519. doi: 10.1073/pnas.1616904114. Epub 2017 Feb 21.
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.
我们研究了重力对巨型肥皂泡的影响，并表明在临界尺寸[公式：见正文]以上重力作用变得显著，其中[公式：见正文]是肥皂膜的平均厚度，[公式：见正文]是毛细长度（[公式：见正文]代表气液表面张力，[公式：见正文]代表液体密度）。我们首先通过实验表明，大肥皂泡不会保持球形，而是在增大尺寸时会变平。然后建立了一个理论模型来解释这种效应，基于力学平衡预测其形状。与液滴形成鲜明对比的是，我们表明巨型气泡形状的高度没有力学限制。在实际中，表面活性剂分子施加的物理化学限制限制了进入这个大渐近域。然而，通过精确类比，展示了如何通过大型充气结构实现巨型气泡形状。
