Abstract:

Dynamic formation and detachment of drop from a capillary tube at low flow rate was investigated by the method of numerical simulation.The full transient process of the formation and detachment of drop was simulated numerically by solving the NavierStokes equations using an algorithm based on the finite volume method.The tracking of the free surface was achieved using the volume of fluid (VOF）technique and the geometric reconstruction was based on the technique of piecewiselinear interface construction (PLIC).Dimensionless elongation length and dimensionless minimum radius against relative time scale was analyzed in the present work and there is a good agreement between the numerical simulation results and experimental results.Not only the development of shape and axial velocity, but also the relationship between the formation and annihilation of the vortex rings in the droplet was investigated.The relation of the pressure on the axial line and the position of the neck and pinchoff of the droplet was investigated by studying the variance of pressure on the axial line.

Key words: 液滴形成, 液滴破碎, VOF方法, 数值模拟

摘要：

采用数值模拟的方法，对在重力作用下微管末端液滴缓慢形成及脱落的动力学过程进行分析和研究。采用有限体积法在轴对称坐标系下求解液滴形成与破碎过程的NavierStokes方程，采用VOF〖DK〗（volume of fluid）方法以及基于PLIC〖DK〗（piecewiselinear interface construction）的几何重构方法追踪液滴运动过程的自由表面，捕捉气液界面的演化过程。分析了量纲1液滴最小颈宽以及量纲1液滴高度等相关特征量随相对时间的变化规律，并与实验结果进行了比较。分析了液滴形貌与液滴轴心线上流向速度的变化以及液滴内部涡环形成与湮灭的关系。通过研究轴心线上压力随时间的变化，分析了压力与液滴颈部位置及断裂位置的关系。

关键词: 液滴形成, 液滴破碎, VOF方法, 数值模拟