单液膜气泡聚并和连接过程的移动粒子半隐式法数值模拟

Numerical Simulation of Moving Particle Semi-Implicit Method for Single-Film Bubbles Coalescence and Connection

为了研究单液膜气泡单层液膜包裹气体的特殊结构形式和内外壁面均受气液表面张力的特殊力学形式,在拉格朗日框架下采用无网格移动粒子半隐式法并基于表面自由能表面张力模型,建立了单液膜双气液界面表面张力模型,从而实现了单液膜气泡振荡变形过程中的复杂界面计算和捕捉。在此基础上对2个单液膜气泡的聚并和连接过程进行了模拟分析,获得了典型的流动现象和液膜变形特征与规律,发现减小表面张力系数或增大黏性系数均会减弱气泡变形过程中表面张力项的变形主导作用。为此,提出了凹点切线法用于计算连接型气泡的液膜夹角,明晰了连接型气泡的形状。计算结果可为工业消泡技术提供一定的理论依据。

The mesh-less moving particle semi-implicit method is employed within the Lagrangian framework to investigate the special geometry of the single film bubble with gas being shrouded by a layer of liquid film,and its special dynamic characteristic that surface tension acts both on the inside and outside interfaces.A surface tension model of the single-film-double-interfaces is established based on the surface tension model of surface free energies,and the complex interface movement in the oscillation process of the single-film bubble is calculated and captured.Moreover,the coalescence and connection process of two single-film bubbles are simulated and analyzed,and the typical flow phenomena and deformation characteristics of the liquid film are obtained.Results show that the leading role of the surface tension in the bubble deforming process reduces when either the surface tension coefficient decreases or the fluid viscosity increases.Furthermore,a concave tangent method is proposed to calculate the angle of the liquid film of the connected bubbles, which helps to describe the shape of connected bubble,quantitatively.These results provide some theoretical supports to the industrial froth breaking.