摘要
采用Level Set方法,三维直接数值模拟了浮力作用下单个气泡的上升运动.数值模拟中,气液系统的物性参数设置为埃奥特沃斯数Eo=1～103,莫顿数Mo=10-10～102.数值研究了气泡的初始形状对气泡的变形和上升速度的影响,并与文献中结果进行了比较;给出了高Eo时气泡由球帽状转变为气泡环的结构相图,确定了二者形状转变的Eo和Mo;最后详细分析了初始形状影响气泡动力学特性的机理.模拟结果表明:低Eo(Eo<52)时浮升气泡的终端形状与上升速度基本不受初始形状的影响;高Eo和低Mo时的浮升气泡受初始形状的支配,呈现出球帽状和气泡环两种最终形状,初始气泡的高宽比越大,气泡越容易变形为气泡环,上升速度的脉动也越剧烈.
Three-dimensional direct numerical simulation on a single bubble rising by buoyancy in viscous liquids was carried out with the level set method. The effect of initial bubble shape on the bubble dynamics was studied numerically with Eotvos number Eo= 1-10^3 and Morton number Mo =10^-10-10^2, and the influencing mechanism was explained in detail. The bubble shape and rise velocity predicted by the simulation agree with a well-known bubble regime phase diagram in lit- erature. In addition, a phase map was also established at high Eo to provide quantitative analysis on the transition of final bubble topology from spherical-cap to toroidal bubble. The numerical resuits show that the final shape and rise velocity are not affected by the initial bubble shape at low Eo（Eo〈52）, while the final bubble state appears to be the spherical-cap and toroidal bubble and is influenced by initial bubble shape at high Eo and low Mo. The bubble is easier to become a toroidal bubble and the temporal fluctuation of bubble rise velocity is stronger when the aspect ratio of the initial bubble is greater.
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
2011年第1期43-47,共5页
Journal of Xi'an Jiaotong University
基金
国家自然科学基金资助项目(20706007)
城市水资源与水环境国家重点实验室开放基金资助项目(QA200806)
中央高校基本科研业务专项基金资助项目(CHD2009JC011)
关键词
浮升气泡
初始形状
相图
数值模拟
buoyancy-driven bubble
initial shape
phase diagram
numerical simulation
