SCI和EI收录∣中国化工学会会刊

Chinese Journal of Chemical Engineering ›› 2016, Vol. 24 ›› Issue (1): 63-70.DOI: 10.1016/j.cjche.2015.07.016

• 第25届中国过程控制会议专栏 • 上一篇    下一篇

Asymmetric breakup of a droplet in an axisymmetric extensional flow

Dongming Yu1,2, Manman Zheng1, Taoming Jin1, Jingtao Wang1   

  1. 1 School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China;
    2 Sinopec Shanghai Engineering Co., Ltd., Shanghai 200120, China
  • 收稿日期:2014-11-16 修回日期:2015-05-30 出版日期:2016-01-28 发布日期:2016-02-23
  • 通讯作者: Jingtao Wang
  • 基金资助:

    Supported by Major State Basic Research Development Program of China (2012CB720305), and the National Natural Science Foundation of China (21376162).

Asymmetric breakup of a droplet in an axisymmetric extensional flow

Dongming Yu1,2, Manman Zheng1, Taoming Jin1, Jingtao Wang1   

  1. 1 School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China;
    2 Sinopec Shanghai Engineering Co., Ltd., Shanghai 200120, China
  • Received:2014-11-16 Revised:2015-05-30 Online:2016-01-28 Published:2016-02-23
  • Contact: Jingtao Wang
  • Supported by:

    Supported by Major State Basic Research Development Program of China (2012CB720305), and the National Natural Science Foundation of China (21376162).

摘要: The asymmetric breakups of a droplet in an axisymmetric cross-like microfluidic device are investigated by using a three-dimensional volume of fluid (VOF) multiphase numerical model. Two kinds of asymmetries (droplet location deviation from the symmetric geometry center and different flow rates at two symmetric outlets) generate asymmetric flow fields near the droplet, which results in the asymmetric breakup of the latter. Four typical breakup regimes (no breakup, one-side breakup, retraction breakup and direct breakup) have been observed. Two regime maps are plotted to describe the transition from one regime to another for the two types of different asymmetries, respectively. A power lawmodel, which is based on the three critical factors (the capillary number, the asymmetry of flow fields and the initial volume ratio), is employed to predict the volume ratio of the two unequal daughter droplets generated in the direct breakup. The influences of capillary numbers and the asymmetries have been studied systematically in this paper. The larger the asymmetry is, the bigger the oneside breakup zone is. The larger the capillary number is, the more possible the breakup is in the direct breakup zone. When the radius of the initial droplet is 20 μm, the critical capillary numbers are 0.122, 0.128, 0.145, 0.165, 0.192 and 0.226 for flow asymmetry factor AS = 0.05, 0.1, 0.2, 0.3, 0.4 and 0.5, respectively, in the flow systemwhose asymmetry is generated by location deviations. In the flowsystemwhose asymmetry is generated by two different flow rates at two outlets, the critical capillary numbers are 0.121, 0.133, 0.145, 0.156 and 0.167 for AS = 1/21, 3/23, 1/5, 7/27 and 9/29, respectively.

关键词: Asymmetric breakup, Droplet, Volume of fluid method, Axisymmetric extensional flow

Abstract: The asymmetric breakups of a droplet in an axisymmetric cross-like microfluidic device are investigated by using a three-dimensional volume of fluid (VOF) multiphase numerical model. Two kinds of asymmetries (droplet location deviation from the symmetric geometry center and different flow rates at two symmetric outlets) generate asymmetric flow fields near the droplet, which results in the asymmetric breakup of the latter. Four typical breakup regimes (no breakup, one-side breakup, retraction breakup and direct breakup) have been observed. Two regime maps are plotted to describe the transition from one regime to another for the two types of different asymmetries, respectively. A power lawmodel, which is based on the three critical factors (the capillary number, the asymmetry of flow fields and the initial volume ratio), is employed to predict the volume ratio of the two unequal daughter droplets generated in the direct breakup. The influences of capillary numbers and the asymmetries have been studied systematically in this paper. The larger the asymmetry is, the bigger the oneside breakup zone is. The larger the capillary number is, the more possible the breakup is in the direct breakup zone. When the radius of the initial droplet is 20 μm, the critical capillary numbers are 0.122, 0.128, 0.145, 0.165, 0.192 and 0.226 for flow asymmetry factor AS = 0.05, 0.1, 0.2, 0.3, 0.4 and 0.5, respectively, in the flow systemwhose asymmetry is generated by location deviations. In the flowsystemwhose asymmetry is generated by two different flow rates at two outlets, the critical capillary numbers are 0.121, 0.133, 0.145, 0.156 and 0.167 for AS = 1/21, 3/23, 1/5, 7/27 and 9/29, respectively.

Key words: Asymmetric breakup, Droplet, Volume of fluid method, Axisymmetric extensional flow