三维格子Boltzmann方法研究上升双气泡的运动特性

应用格子Boltzmann三维模型,对双气泡在静水中的运动进行数值研究.采用八点差分和十八点差分格式分别求解一阶▽?和二阶▽^2?可以有效避免气液密度比过大造成的数值不稳定问题.结果表明:当两个相同直径的气泡在上升时,位置靠上的气泡形状变化像单气泡上升一样,而位置靠下的气泡会受到前一个气泡尾迹的影响,并有很明显的形状变化.当两个气泡直径不同时,不管初始位置如何,大气泡总会对小气泡造成强烈的影响.

Three-dimensional Numerical Simulation of Dynamics Characteristics of Two Rising Bubbles with Lattice Boltzmann Method

Dynamics characteristics of two bubbles in a quiescent fluid were simulated with three-dimensional lattice Boltzmann model. Eight-point and eighteen-point difference schemes were used to calculate the first and the second order derivative ▽ φ and ▽²φ in order to avoid numerical instability caused by large density ratios. It shows that for two rising bubbles with same size, the leading bubble rises like an isolated bubble, and the trailing bubble is influenced by the wake of the leading bubble. For two rising bubbles with different sizes, however, the larger bubble always strongly affects the smaller one in any initial sizes and locations.