Thomas Gilberto L, Belmonte Julio M, Graner François, Glazier James A, de Almeida Rita M C
Instituto de Física, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, C.P. 15051 - 91501-970 Porto Alegre, RS, Brazil.
European Molecular Biology Laboratory Heidelberg, Meyerhofstr. 1, 69117 Heidelberg, Germany; Biocomplexity Institute and Department of Physics, Indiana University Bloomington, Bloomington, Indiana, 47405, United States of America.
Colloids Surf A Physicochem Eng Asp. 2015 May 20;473:109-114. doi: 10.1016/j.colsurfa.2015.02.015. Epub 2015 Feb 14.
In wet liquid foams, slow diffusion of gas through bubble walls changes bubble pressure, volume and wall curvature. Large bubbles grow at the expenses of smaller ones. The smaller the bubble, the faster it shrinks. As the number of bubbles in a given volume decreases in time, the average bubble size increases: the foam coarsens. During coarsening, bubbles also move relative to each other, changing bubble topology and shape, while liquid moves within the regions separating the bubbles. Analyzing the combined effects of these mechanisms requires examining a volume with enough bubbles to provide appropriate statistics throughout coarsening. Using a Cellular Potts model, we simulate these mechanisms during the evolution of three-dimensional foams with wetnesses of = 0.00, 0.05 and 0.20. We represent the liquid phase as an ensemble of many small fluid particles, which allows us to monitor liquid flow in the region between bubbles. The simulations begin with 2 × 10 bubbles for = 0.00 and 1.25 × 10 bubbles for = 0.05 and 0.20, allowing us to track the distribution functions for bubble size, topology and growth rate over two and a half decades of volume change. All simulations eventually reach a growth regime, with the distribution functions time independent and the number of bubbles decreasing with time as a power law whose exponent depends on the wetness.
在湿液体泡沫中，气体通过泡壁的缓慢扩散会改变气泡压力、体积和壁曲率。大泡泡以小泡泡为代价生长。泡泡越小，收缩得越快。随着给定体积内气泡数量随时间减少，平均气泡尺寸增大：泡沫粗化。在粗化过程中，气泡也会相对彼此移动，改变气泡拓扑结构和形状，同时液体在分隔气泡的区域内流动。分析这些机制的综合影响需要考察一个包含足够气泡的体积，以便在整个粗化过程中提供适当的统计数据。我们使用细胞Potts模型，模拟了湿度分别为 = 0.00、0.05和0.20的三维泡沫演化过程中的这些机制。我们将液相表示为许多小流体粒子的集合，这使我们能够监测气泡之间区域的液体流动。对于 = 0.00的情况，模拟从2×10个气泡开始；对于 = 0.05和0.20的情况，从1.25×10个气泡开始，这使我们能够跟踪两个半数量级体积变化范围内气泡尺寸、拓扑结构和生长速率的分布函数。所有模拟最终都达到一个生长状态，分布函数与时间无关，气泡数量随时间以幂律形式减少，其指数取决于湿度。
