Maurdev G, Saint-Jalmes A, Langevin D
Laboratoire de Physique des Solides, Université Paris-Sud, 91405 Orsay Cedex, France.
J Colloid Interface Sci. 2006 Aug 15;300(2):735-43. doi: 10.1016/j.jcis.2006.03.079. Epub 2006 May 4.
We have studied bubble motion within a column of foam allowed to undergo free drainage. We have measured bubble motion upward with time and as a function of their initial positions. Depending on the gas used, which sets the coarsening and drainage rates, different bubble upward motion types have been identified (constant speed, acceleration or deceleration) and explained in relation with liquid downward flows. The proofs of the consistency between bubble upward motion and liquid downward flow are obtained both by comparing the bubble motion curves to the liquid drainage ones, and by comparing the time variations of the liquid fraction extracted from bubble motion to direct liquid fraction measurements by electrical conductimetry. The agreement between bubble position tracking and electrical conductivity shows in particular that it is possible to determine the drainage regime from such simple bubble motion measurements. This work also allowed us to demonstrate a special case of foam coarsening and expansion, occurring when the foam gas is less soluble than the outside one, caused by diffusion of this external gas into the foam. All these results allow us to build a picture of drainage and coarsening seen from the bubble point of view.
我们研究了在允许自由排水的泡沫柱内的气泡运动。我们测量了气泡随时间以及作为其初始位置函数的向上运动。根据所使用的气体（它决定了粗化和排水速率），已识别出不同的气泡向上运动类型（恒定速度、加速或减速），并结合液体向下流动进行了解释。通过将气泡运动曲线与液体排水曲线进行比较，以及将从气泡运动中提取的液体分数的时间变化与通过电导率法进行的直接液体分数测量进行比较，获得了气泡向上运动与液体向下流动之间一致性的证据。气泡位置跟踪与电导率之间的一致性尤其表明，通过这种简单的气泡运动测量可以确定排水状态。这项工作还使我们能够证明一种特殊情况的泡沫粗化和膨胀，即当泡沫气体的溶解度低于外部气体时，由这种外部气体扩散到泡沫中引起的情况。所有这些结果使我们能够从气泡的角度构建一幅排水和粗化的图景。
