Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA.
Department of Applied Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Science. 2020 Aug 7;369(6504):685-688. doi: 10.1126/science.aba0593.
Viscous bubbles are prevalent in both natural and industrial settings. Their rupture and collapse may be accompanied by features typically associated with elastic sheets, including the development of radial wrinkles. Previous investigators concluded that the film weight is responsible for both the film collapse and wrinkling instability. Conversely, we show here experimentally that gravity plays a negligible role: The same collapse and wrinkling arise independently of the bubble's orientation. We found that surface tension drives the collapse and initiates a dynamic buckling instability. Because the film weight is irrelevant, our results suggest that wrinkling may likewise accompany the breakup of relatively small-scale, curved viscous and viscoelastic films, including those in the respiratory tract responsible for aerosol production from exhalation events.
粘性气泡在自然和工业环境中都很常见。它们的破裂和坍塌可能伴随着通常与弹性片相关的特征，包括径向皱纹的发展。以前的研究人员得出结论，薄膜重量是导致薄膜坍塌和起皱不稳定的原因。相反，我们在这里通过实验表明，重力的作用可以忽略不计：相同的坍塌和起皱独立于气泡的方向出现。我们发现，表面张力驱动着坍塌，并引发了动态屈曲不稳定性。由于薄膜重量无关紧要，我们的结果表明，褶皱可能同样伴随着相对较小尺度的粘性和粘弹性薄膜的破裂，包括呼吸道中导致呼气事件产生气溶胶的那些薄膜。
