-
基于体积分数法建立了Y型微通道中双重乳液流动非稳态理论模型, 数值模拟研究了Y型微通道内双重乳液破裂情况, 详细分析了双重乳液流经Y型微通道时的流场信息以及双重乳液形变参数演化特性, 定量地给出了双重乳液流动破裂的驱动以及阻碍作用, 揭示了双重乳液破裂流型的内在机理. 研究结果表明: 流经Y型微通道时, 双重乳液受上游压力驱动产生形变, 形变过程中乳液两端界面张力差阻碍双重乳液形变破裂, 两者正相关; 隧道的出现将减缓双重乳液外液滴颈部收缩速率以及沿流向拉伸的速率, 并减缓了内液滴沿流向拉伸的速率, 其对于内液滴颈部收缩速率影响不大; 隧道破裂和不破裂工况临界线可以采用幂律关系式
${l^*} = \beta C{a^b}$ 进行预测, 隧道破裂和阻塞破裂工况临界线可以采用线性关系${l^*} = \alpha $ 描述; 与单乳液运动相图相比, 双重乳液运动相图各工况的分界线关系式系数$\alpha $ 和$\beta $ 均相应增大.A scheme of passive breakup of generated droplet into two daughter droplets in a microfluidic Y-junction is characterized by the precisely controlling the droplet size distribution. Compared with the T-junction, the microfluidic Y-junction is very convenient for droplet breakup and successfully applied to double emulsion breakup. Therefore, it is of theoretical significance and engineering value for fully understanding the double emulsion breakup in a Y-junction. However, current research mainly focuses on the breakup of single phase droplet in the Y-junction. In addition, due to structural complexity, especially the existence of the inner droplet, more complicated hydrodynamics and interface topologies are involved in the double emulsion breakup in a Y-junction than the scenario of the common single phase droplet. For these reasons, an unsteady model of a double emulsion passing through microfluidic Y-junction is developed based on the volume of fluid method and numerically analyzed to investigate the dynamic behavior of double emulsion passing through a microfluidic Y-junction. The detailed hydrodynamic information about the breakup and non-breakup is presented, together with the quantitative evolutions of driving and resistance force as well as the droplet deformation characteristics, which reveals the hydrodynamics underlying the double emulsion breakup. The results indicate that the three flow regimes are observed when double emulsion passes through a microfluidic Y-junction: obstructed breakup, tunnel breakup and non-breakup; as the capillary number or initial length of the double emulsion decreases, the flow regime transforms from tunnel breakup to non-breakup; the upstream pressure and the Laplace pressure difference between the forefront and rear droplet interfaces, which exhibit a correspondence relationship, are regarded as the main driving force and the resistance to double emulsion breakup through a microfluidic Y-junction; the appearance of tunnels affects the double emulsion deformation, resulting in the slower squeezing speed and elongation speed of outer droplet as well as the slower squeezing speed of inner droplet; the critical threshold between breakup and non-breakup is approximately expressed as a power-law formula${l^*} = \beta C{a^b}$ , while the threshold between tunnel breakup and obstructed breakup is approximately expressed as a linear formula${l^*} = \alpha $ ; comparing with the phase diagram for single phase droplet, the coefficients$\alpha $ and$\beta $ of the boundary lines between the different regimes in phase diagram for double emulsion are both increased.-
Keywords:
- Y-junction /
- double emulsion /
- breakup /
- volume of fluid method
[1] Shum H C, Bandyopadhyay A, Bose S, Weitz D A 2009 Chem. Mater. 21 5548Google Scholar
[2] Chen H S, Zhao Y J, Li J, Guo M, Wan J D, Weitz D A, Stone H A 2011 Lab Chip 11 2312Google Scholar
[3] Kim S H, Kim J W, Cho J C, Weitz D A 2011 Lab Chip 11 3162Google Scholar
[4] Wang J, Sun L, Zou M, Gao W, Liu C, Shang L, Gu Z, Zhao Y 2017 Sci. Adv. 3 e1700004
[5] Kim J H, Jeon T Y, Choi T M, Shim T S, Kim S H, Yang S M 2014 Langmuir 30 1473Google Scholar
[6] McClements D J, Li Y 2010 Adv. Colloid Interface Sci. 159 213
[7] Zhang Y, Chan H F, Leong K W 2013 Adv. Drug Del. Rev. 65 104Google Scholar
[8] Teh S Y, Lin R, Hung L H, Lee A P 2008 Lab Chip 8 198Google Scholar
[9] Seemann R, Brinkmann M, Pfohl T, Herminghaus S 2012 Rep. Prog. Phys. 75 016601Google Scholar
[10] Shang L R, Cheng Y, Zhao Y J 2017 Chem. Rev. 117 7964Google Scholar
[11] Choi C H, Kim J, Nam J O, Kang S M, Jeong S G, Lee C S 2014 Chemphyschem 15 21Google Scholar
[12] Vladisavljevic G T, Al Nuumani R, Nabavi S A 2017 Micromachines 8 75Google Scholar
[13] Cubaud T 2009 Phys. Rev. E 80 026307Google Scholar
[14] Link D R, Anna S L, Weitz D A, Stone H A 2004 Phys. Rev. Lett. 92 054503Google Scholar
[15] de Menech M 2006 Phys. Rev. E 73 031505Google Scholar
[16] Jullien M C, Ching M J T M, Cohen C, Menetrier L, Tabeling P 2009 Phys. Fluids 21 072001Google Scholar
[17] Leshansky A M, Pismen L M 2009 Phys. Fluids 21 023303Google Scholar
[18] Afkhami S, Leshansky A M, Renardy Y 2011 Phys. Fluids 23 022002Google Scholar
[19] Leshansky A M, Afkhami S, Jullien M C, Tabeling P 2012 Phys. Rev. Lett. 108 264502Google Scholar
[20] Hoang D A, Portela L M, Kleijn C R, Kreutzer M T, van Steijn V 2013 J. Fluid Mech. 717 R4Google Scholar
[21] Samie M, Salari A, Shafii M B 2013 Phys. Rev. E 87 053003Google Scholar
[22] Chen B, Li G J, Wang W M, Wang P 2015 Appl. Therm. Eng. 88 94Google Scholar
[23] Chen Y P, Deng Z L 2017 J. Fluid Mech. 819 401Google Scholar
[24] Yamada M, Doi S, Maenaka H, Yasuda M, Seki M 2008 J. Colloid Interface Sci. 321 401Google Scholar
[25] Carlson A, Do Quang M, Amberg G 2010 Int. J. Multiphase Flow 36 397Google Scholar
[26] Abate A R, Weitz D A 2011 Lab Chip 11 1911Google Scholar
[27] 梁宏, 柴振华, 施保昌 2016 物理学报 65 204701Google Scholar
Liang H, Chai Z H, Shi B C 2016 Acta Phys. Sin. 65 204701Google Scholar
[28] Wang Y, Minh D Q, Amberg G 2016 Phys. Fluids 28 033103Google Scholar
[29] Zheng M M, Ma Y L, Jin T M, Wang J T 2016 Microfluid. Nanofluid. 20 107Google Scholar
[30] Ma Y L, Zheng M M, Bah M G, Wang J T 2018 Chem. Eng. Sci. 179 104Google Scholar
[31] Chen Y P, Gao W, Zhang C B, Zhao Y J 2016 Lab Chip 16 1332Google Scholar
[32] Chen Y P, Liu X D, Shi M H 2013 Appl. Phys. Lett. 102 051609Google Scholar
[33] Bashir S, Rees J M, Zimmerman W B 2014 Int. J. Multiphase Flow 60 40Google Scholar
[34] Chen Y P, Wu L Y, Zhang L 2015 Int. J. Heat Mass Transfer 82 42Google Scholar
[35] Nabavi S A, Gu S, Vladisavljevic G T, Ekanem E E 2015 J. Colloid Interface Sci. 450 279Google Scholar
[36] Nabavi S A, Vladisavljevic G T, Gu S, Ekanem E E 2015 Chem. Eng. Sci. 130 183Google Scholar
[37] Azarmanesh M, Farhadi M, Azizian P 2016 Phys. Fluids 28 032005Google Scholar
[38] Fu Y H, Zhao S F, Bai L, Jin Y, Cheng Y 2016 Chem. Eng. Sci. 146 126Google Scholar
[39] Liu X D, Wu L Y, Zhao Y J, Chen Y P 2017 Colloids Surf. Physicochem. Eng. Aspects 533 87Google Scholar
[40] Chen Y P, Liu X D, Zhao Y J 2015 Appl. Phys. Lett. 106 141601Google Scholar
[41] 张程宾, 于程, 刘向东, 金瓯, 陈永平 2016 物理学报 65 204704Google Scholar
Zhang C B, Yu C, Liu X D, Jin O, Chen Y P 2016 Acta Phys. Sin. 65 204704Google Scholar
[42] Liu X D, Wang C Y, Zhao Y J, Chen Y P 2018 Chem. Eng. Sci. 183 215Google Scholar
[43] Liu X D, Wang C Y, Zhao Y J, Chen Y P 2018 Int. J. Heat Mass Transfer 121 377Google Scholar
[44] Brackbill J U, Kothe D B, Zemach C 1992 J. Comput. Phys. 100 335Google Scholar
[45] Gueyffier D, Li J, Nadim A, Scardovelli R, Zaleski S 1999 J. Comput. Phys. 152 423Google Scholar
[46] Taylor G I 1934 Proc. Roy. Soc. London Series A 146 501Google Scholar
-
图 5 模拟结果与实验结果[41]对比 (a) 双重乳液的形变参数D随Ca的变化; (b) 双重乳液形貌对比
Fig. 5. Comparison of steady deformation of double emulsion between simulation and experiment[41]: (a) Steady deformation of double emulsion in the function of Ca; (b) comparison of droplet morphology reconstructed from numerical simulation with experimental snapshots.
图 7 阻塞破裂工况乳液前端及尾部界面张力演化情况(Ca = 0.01, Voi = 1.3, l* = 2.1) (a) 乳液前端界面张力; (b) 乳液尾部界面张力; (c) 乳液前端与尾部界面张力之差; (d) 特征时刻乳液前端与尾部界面张力的示意图
Fig. 7. Evolution of the pressure for obstructed breakup (Ca = 0.01, Voi = 1.3, l* = 2.1): (a) The Laplace pressure of the forefront droplet interface; (b) the Laplace pressure of the rear droplet interface; (c) the Laplace pressure difference between the forefront and rear droplet interfaces; (d) schematics of
$\Delta {p_{\sigma ,{\rm{front}}}}$ and$\Delta {p_{\sigma ,{\rm{tail}}}}$ at different times.图 9 双重乳液无量纲特征参数在squeezing阶段内演化情况 (Ca = 0.01, Voi = 1.3, l* = 2.1) (a)外液滴颈部厚度
$\delta _{{\rm{out}}}^*$ , 插图中给出了$\delta _{{\rm{out}},0}^{\rm{*}} - \delta _{{\rm{out}}}^*$ 与${t^*} - t_{{\rm{out}},0}^{\rm{*}}$ 的对数坐标图; (b) 外液滴前端运动距离$\Delta l_{{\rm{out}}}^*$ , 插图中给出了$\Delta l_{{\rm{out}}}^*$ 与${t^*} - t_{{\rm{out}},0}^{\rm{*}}$ 的对数坐标图; (c) 内液滴颈部厚度$\delta _{{\rm{in}}}^*$ , 插图中给出了$\delta _{{\rm{in}},0}^{\rm{*}} - \delta _{{\rm{in}}}^*$ 与${t^*} - t_{{\rm{in}},0}^{\rm{*}}$ 的对数坐标图; (d) 内液滴前端运动距离$\Delta l_{{\rm{in}}}^*$ , 插图中给出了$\Delta l_{{\rm{in}}}^*$ 与${t^*} - t_{{\rm{in}},0}^{\rm{*}}$ 的对数坐标图Fig. 9. Evolution of the dimensionless characteristic parameters in the squeezing stage for obstructed breakup (Ca = 0.01, Voi = 1.3, l* = 2.1): (a)The neck thickness of outer droplet
$\delta _{{\rm{out}}}^*$ , inset is the same data as log($\delta _{{\rm{out}},0}^{\rm{*}} - \delta _{{\rm{out}}}^*$ ) versus log(${t^*} - t_{{\rm{out}},0}^{\rm{*}}$ ); (b) the distance travelled by the tip of outer droplet$\Delta l_{{\rm{out}}}^*$ , the same data as log($\Delta l_{{\rm{out}}}^*$ ) versus log(${t^*} - t_{{\rm{out}},0}^{\rm{*}}$ ); (c) the neck thickness of inner droplet$\delta _{{\rm{in}}}^*$ , inset is the same data as log($\delta _{{\rm{in}},0}^{\rm{*}} - \delta _{{\rm{in}}}^*$ ) versus log(${t^*} - t_{{\rm{in}},0}^{\rm{*}}$ ); (b) the distance travelled by the tip of inner droplet$\Delta l_{{\rm{in}}}^*$ , the same data as log($\Delta l_{{\rm{in}}}^*$ ) versus log(${t^*} - t_{{\rm{in}},0}^{\rm{*}}$ ).图 11 隧道破裂工况乳液前端及尾部界面张力演化情况 (Ca = 0.01, Voi = 1.3, l* = 1.3) (a) 乳液前端界面张力; (b) 乳液尾部界面张力; (c) 乳液前端与尾部界面张力之差
Fig. 11. Evolution of the pressure for tunnel breakup (Ca = 0.01, Voi = 1.3, l* = 1.3): (a) The Laplace pressure of the forefront droplet interface; (b) the Laplace pressure of the rear droplet interface; (c) the Laplace pressure difference between the forefront and rear droplet interfaces.
图 13 隧道破裂工况双重乳液无量纲特征参数在squeezing 阶段内演化情况 (Ca = 0.01, Voi = 1.3, l* = 1.3) (a) 外液滴颈部厚度
$\delta _{{\rm{out}}}^*$ , 插图中给出了$\delta _{{\rm{out}},0}^{\rm{*}} - \delta _{{\rm{out}}}^*$ 与${t^*} - t_{{\rm{out}},0}^{\rm{*}}$ 的对数坐标图; (b) 外液滴前端运动距离$\Delta l_{{\rm{out}}}^*$ , 插图中给出了$\Delta l_{{\rm{out}}}^*$ 与${t^*} - t_{{\rm{out}},0}^{\rm{*}}$ 的对数坐标图; (c) 内液滴颈部厚度$\delta _{{\rm{in}}}^*$ , 插图中给出了$\delta _{{\rm{in}},0}^{\rm{*}} - \delta _{{\rm{in}}}^*$ 与${t^*} - t_{{\rm{in}},0}^{\rm{*}}$ 的对数坐标图; (d) 内液滴前端运动距离$\Delta l_{{\rm{in}}}^*$ , 插图中给出了$\Delta l_{{\rm{in}}}^*$ 与${t^*} - t_{{\rm{in}},0}^{\rm{*}}$ 的对数坐标图Fig. 13. Evolution of the dimensionless characteristic parameters in the squeezing stage for tunnel breakup (Ca = 0.01, Voi = 1.3, l* = 1.3): (a) The neck thickness of outer droplet
$\delta _{{\rm{out}}}^*$ , inset is the same data as log($\delta _{{\rm{out}},0}^{\rm{*}} - \delta _{{\rm{out}}}^*$ ) versus log(${t^*} - t_{{\rm{out}},0}^{\rm{*}}$ ); (b) the distance travelled by the tip of outer droplet$\Delta l_{{\rm{out}}}^*$ , the same data as log($\Delta l_{{\rm{out}}}^*$ ) versus log(${t^*} - t_{{\rm{out}},0}^{\rm{*}}$ ); (c) the neck thickness of inner droplet$\delta _{{\rm{in}}}^*$ , inset is the same data as log($\delta _{{\rm{in}},0}^{\rm{*}} - \delta _{{\rm{in}}}^*$ ) versus log(${t^*} - t_{{\rm{in}},0}^{\rm{*}}$ ); (b) the distance travelled by the tip of inner droplet$\Delta l_{{\rm{out}}}^*$ , the same data as log($\Delta l_{{\rm{in}}}^*$ ) versus log(${t^*} - t_{{\rm{in}},0}^{\rm{*}}$ ).表 1 数值模拟中各相流体的物性参数
Table 1. The properties of the fluids used for numerical simulation.
相 密度/kg·m–3 黏度/mPa·s 内相 1107 7.91 中间相 940 10.37 外相 1012 1.24 -
[1] Shum H C, Bandyopadhyay A, Bose S, Weitz D A 2009 Chem. Mater. 21 5548Google Scholar
[2] Chen H S, Zhao Y J, Li J, Guo M, Wan J D, Weitz D A, Stone H A 2011 Lab Chip 11 2312Google Scholar
[3] Kim S H, Kim J W, Cho J C, Weitz D A 2011 Lab Chip 11 3162Google Scholar
[4] Wang J, Sun L, Zou M, Gao W, Liu C, Shang L, Gu Z, Zhao Y 2017 Sci. Adv. 3 e1700004
[5] Kim J H, Jeon T Y, Choi T M, Shim T S, Kim S H, Yang S M 2014 Langmuir 30 1473Google Scholar
[6] McClements D J, Li Y 2010 Adv. Colloid Interface Sci. 159 213
[7] Zhang Y, Chan H F, Leong K W 2013 Adv. Drug Del. Rev. 65 104Google Scholar
[8] Teh S Y, Lin R, Hung L H, Lee A P 2008 Lab Chip 8 198Google Scholar
[9] Seemann R, Brinkmann M, Pfohl T, Herminghaus S 2012 Rep. Prog. Phys. 75 016601Google Scholar
[10] Shang L R, Cheng Y, Zhao Y J 2017 Chem. Rev. 117 7964Google Scholar
[11] Choi C H, Kim J, Nam J O, Kang S M, Jeong S G, Lee C S 2014 Chemphyschem 15 21Google Scholar
[12] Vladisavljevic G T, Al Nuumani R, Nabavi S A 2017 Micromachines 8 75Google Scholar
[13] Cubaud T 2009 Phys. Rev. E 80 026307Google Scholar
[14] Link D R, Anna S L, Weitz D A, Stone H A 2004 Phys. Rev. Lett. 92 054503Google Scholar
[15] de Menech M 2006 Phys. Rev. E 73 031505Google Scholar
[16] Jullien M C, Ching M J T M, Cohen C, Menetrier L, Tabeling P 2009 Phys. Fluids 21 072001Google Scholar
[17] Leshansky A M, Pismen L M 2009 Phys. Fluids 21 023303Google Scholar
[18] Afkhami S, Leshansky A M, Renardy Y 2011 Phys. Fluids 23 022002Google Scholar
[19] Leshansky A M, Afkhami S, Jullien M C, Tabeling P 2012 Phys. Rev. Lett. 108 264502Google Scholar
[20] Hoang D A, Portela L M, Kleijn C R, Kreutzer M T, van Steijn V 2013 J. Fluid Mech. 717 R4Google Scholar
[21] Samie M, Salari A, Shafii M B 2013 Phys. Rev. E 87 053003Google Scholar
[22] Chen B, Li G J, Wang W M, Wang P 2015 Appl. Therm. Eng. 88 94Google Scholar
[23] Chen Y P, Deng Z L 2017 J. Fluid Mech. 819 401Google Scholar
[24] Yamada M, Doi S, Maenaka H, Yasuda M, Seki M 2008 J. Colloid Interface Sci. 321 401Google Scholar
[25] Carlson A, Do Quang M, Amberg G 2010 Int. J. Multiphase Flow 36 397Google Scholar
[26] Abate A R, Weitz D A 2011 Lab Chip 11 1911Google Scholar
[27] 梁宏, 柴振华, 施保昌 2016 物理学报 65 204701Google Scholar
Liang H, Chai Z H, Shi B C 2016 Acta Phys. Sin. 65 204701Google Scholar
[28] Wang Y, Minh D Q, Amberg G 2016 Phys. Fluids 28 033103Google Scholar
[29] Zheng M M, Ma Y L, Jin T M, Wang J T 2016 Microfluid. Nanofluid. 20 107Google Scholar
[30] Ma Y L, Zheng M M, Bah M G, Wang J T 2018 Chem. Eng. Sci. 179 104Google Scholar
[31] Chen Y P, Gao W, Zhang C B, Zhao Y J 2016 Lab Chip 16 1332Google Scholar
[32] Chen Y P, Liu X D, Shi M H 2013 Appl. Phys. Lett. 102 051609Google Scholar
[33] Bashir S, Rees J M, Zimmerman W B 2014 Int. J. Multiphase Flow 60 40Google Scholar
[34] Chen Y P, Wu L Y, Zhang L 2015 Int. J. Heat Mass Transfer 82 42Google Scholar
[35] Nabavi S A, Gu S, Vladisavljevic G T, Ekanem E E 2015 J. Colloid Interface Sci. 450 279Google Scholar
[36] Nabavi S A, Vladisavljevic G T, Gu S, Ekanem E E 2015 Chem. Eng. Sci. 130 183Google Scholar
[37] Azarmanesh M, Farhadi M, Azizian P 2016 Phys. Fluids 28 032005Google Scholar
[38] Fu Y H, Zhao S F, Bai L, Jin Y, Cheng Y 2016 Chem. Eng. Sci. 146 126Google Scholar
[39] Liu X D, Wu L Y, Zhao Y J, Chen Y P 2017 Colloids Surf. Physicochem. Eng. Aspects 533 87Google Scholar
[40] Chen Y P, Liu X D, Zhao Y J 2015 Appl. Phys. Lett. 106 141601Google Scholar
[41] 张程宾, 于程, 刘向东, 金瓯, 陈永平 2016 物理学报 65 204704Google Scholar
Zhang C B, Yu C, Liu X D, Jin O, Chen Y P 2016 Acta Phys. Sin. 65 204704Google Scholar
[42] Liu X D, Wang C Y, Zhao Y J, Chen Y P 2018 Chem. Eng. Sci. 183 215Google Scholar
[43] Liu X D, Wang C Y, Zhao Y J, Chen Y P 2018 Int. J. Heat Mass Transfer 121 377Google Scholar
[44] Brackbill J U, Kothe D B, Zemach C 1992 J. Comput. Phys. 100 335Google Scholar
[45] Gueyffier D, Li J, Nadim A, Scardovelli R, Zaleski S 1999 J. Comput. Phys. 152 423Google Scholar
[46] Taylor G I 1934 Proc. Roy. Soc. London Series A 146 501Google Scholar
计量
- 文章访问数: 8587
- PDF下载量: 125
- 被引次数: 0