Department of Mechanical Engineering, Boston University, Boston, MA, 02215, USA.
Nat Commun. 2023 Feb 16;14(1):877. doi: 10.1038/s41467-023-36397-0.
Bubbles will rest at the surface of a liquid bath until their spherical cap drains sufficiently to spontaneously rupture. For large film caps, the memory of initial conditions is believed to be erased due to a visco-gravitational flow, whose velocity increases from the top of the bubble to its base. Consequently, the film thickness has been calculated to be relatively uniform as it thins, regardless of whether the drainage is regulated by shear or elongation. Here, we demonstrate that for large bare bubbles, the film thickness is highly nonuniform throughout drainage, spanning orders of magnitude from top to base. We link the film thickness profile to a universal non-monotonic drainage flow that depends on the bubble thinning rate. These results highlight an unexpected coupling between drainage velocity and bubble thickness profiles and provide critical insight needed to understand the retraction and breakup dynamics of these bubbles upon rupture.
气泡将停留在液体浴的表面，直到它们的球形帽充分排干，从而自发破裂。对于大的薄膜帽，由于粘性重力流，初始条件的记忆被认为被擦除，其速度从气泡的顶部增加到其底部。因此，无论排水是由剪切还是拉伸调节，薄膜厚度都被计算为变薄时相对均匀。在这里，我们证明对于大的裸露气泡，在整个排水过程中，薄膜厚度非常不均匀，从顶部到底部跨越几个数量级。我们将薄膜厚度分布与依赖于气泡变薄率的通用非单调排水流联系起来。这些结果突出了排水速度和气泡厚度分布之间的意外耦合，并为理解这些气泡破裂时的回缩和破裂动力学提供了所需的关键见解。
