MECHANISTIC STUDY OF LASER-DRIVEN DROPLET MIGRATION
-
摘要: 液滴热毛细迁移是微重力流体科学中的典型科学问题, 微重力液滴动力学研究不仅具有流体力学的理论意义, 而且具有重要的实际应用价值. 建立了二维轴对称激光驱动液滴迁移模型, 通过仿真计算研究微重力环境下激光驱动液滴迁移的过程, 研究了液滴直径、母液参数等对液滴迁移速度及行为的影响. 首先研究了母液和液滴对激光系数均较小, 液滴初始位置不同时液滴的迁移行为; 然后研究了母液对激光吸收系数较小, 液滴对激光吸收系数较大时, 不同液滴直径与母液宽度比条件下液滴的迁移行为. 仿真结果表明: 当母液和液滴对激光的吸收系数都很小时, 液滴迁移的方向主要受到液滴初始位置的影响; 当母液对激光的吸收系数较小, 液滴对激光的吸收系数较大时, 液滴会朝激光方向迁移, 液滴初始位置对迁移方向影响较小, 但液滴直径与母液宽度之比会影响液滴迁移行为. 将模拟结果与YGB理论对比, 仿真结果与理论结果趋势一致. 研究激光驱动液滴迁移的物理机制, 探索界面张力作用机理, 得到激光驱动液滴迁移的规律, 探索对液滴的驱动控制方法.Abstract: Droplet thermocapillary migration is a typical scientific problem in microgravity fluid science, and the study of microgravity droplet dynamics not only has the theoretical significance of fluid mechanics, but also has important practical value. A two-dimensional axisymmetric laser-driven droplet migration model was established. The laser-driven droplet migration process in microgravity environment is studied by simulation calculations, and the effects of droplet diameter and mother liquor parameters on droplet migration speed and behavior are investigated. Firstly, the migration of the droplets was studied when the mother liquor and the droplets have smaller laser coefficients and the initial positions of the droplets are different; then the migration of the droplets was studied the mother liquor has a smaller laser absorption coefficient and the droplets have a larger laser absorption coefficient and the ratios of the diameter to the width of the mother liquor are different. Simulation results show that when the absorption coefficients of both mother liquor and droplet for laser are small, the direction of droplet migration is mainly influenced by the initial position of the droplet. When the absorption coefficient of the mother liquor to the laser is small and the absorption coefficient of the droplet to the laser is large, the droplet will move toward the laser. The initial position of the droplet has less influence on the migration direction, but the ratio of the droplet diameter to the width of the mother liquor will affect the droplet migration behavior. By comparing with the YGB theory, the simulation results are consistent with the trend of the theoretical results. The physical mechanism of laser-driven droplet migration is studied, the mechanism of interfacial tension effect is explored, the law of laser-driven droplet migration is obtained, and the driving control method for droplets is explored.
-
Key words:
- laser-driven /
- droplet /
- thermocapillary /
- microgravity
-
图 4 不同时间步长下同一工况液滴界面附近母液流速及液滴速度图
Figure 4. Velocity of droplet and mother liquor around droplet interface for the same working condition at different time steps
图 5 液滴初始位置在母液上部时的流线图
Figure 5. Streamline when the initial droplet position droplet is in the upper part of the mother liquor
图 6 液滴初始位置在母液上部液滴界面附近母液流速及液滴速度图
Figure 6. Velocity of droplet and mother liquor around droplet interface when initial droplet position is in the upper part of the mother liquor
图 7 液滴初始位置在母液上部液滴界面附近压力图
Figure 7. Pressure variation around droplet interface when initial droplet position is in the upper part of the mother liquor
图 8 液滴初始位置在母液正中时的流线图
Figure 8. Streamline when the initial droplet position droplet is in the middle of the mother liquor
图 9 液滴初始位置在母液正中液滴界面附近母液流速图
Figure 9. Velocity of droplet and mother liquor around droplet interface when initial droplet position is in the middle of the mother liquor
图 10 液滴初始位置在母液正中液滴界面附近压力图
Figure 10. Pressure variation around droplet interface when initial droplet position is in the middle of the mother liquor
图 11 液滴初始位置在母液下部时的流线图
Figure 11. Streamline when the initial droplet position droplet is in the lower part of the mother liquor
图 12 液滴初始位置在母液下部液滴界面附近母液 流速及液滴速度图
Figure 12. Velocity of droplet and mother liquor around droplet interface when initial droplet position is in the lower part of the mother liquor
图 13 液滴初始位置在母液下部液滴界面附近压力
Figure 13. Pressure variation around droplet interface when initial droplet position is in the lower part of the mother liquor
图 14 液滴初始位置在母液下部时的流线图
Figure 14. Streamline when the initial droplet position droplet is in the lower part of the mother liquor
图 15 液滴初始位置在母液下部液滴界面附近母液流速及液滴速度图
Figure 15. Velocity of droplet and mother liquor around droplet interface when initial droplet position is in the lower part of the mother liquor
图 16 不同Ar时液滴球心距母液底端距离
Figure 16. Distance variation from the center of the droplet sphere to the bottom of the mother liquor with different Ar
图 17 液滴初始位置在母液下部液滴界面附近母液流速及液滴速度图
Figure 17. Velocity of droplet and mother liquor around droplet interface when initial droplet position is in the lower part of the mother liquor
图 18 不同Ar时液滴球心距母液底端距离
Figure 18. Distance variation from the center of the droplet sphere to the bottom of the mother liquor with different Ar
图 19 液滴初始位置在母液下部液滴界面附近母液流速及液滴速度图
Figure 19. Velocity of droplet and mother liquor around droplet interface when initial droplet position is in the lower part of the mother liquor
表 1 物性参数
Table 1. Physical property parameters
ν/
(µm2·s−1)ρ/
( kg·m−3)Λ/
(W·m−1·K−1)σT/
(µN·m−1·K−1)mother liquor 30.0 955 0.151 droplet 2.8 955 0.410 −86.3 
下载: 导出CSV
表 2 不同直径不同温度梯度液滴迁移仿真计算速度与YGB理论迁移速度及Re, Ma对照表
Table 2. Size of droplets, simulation calculation migration velocity, YGB model velocity, Re and Ma
R/mm Г/(K·mm−1) Vmax/(mm·s−1) VYGB/(mm·s−1) Re Ma/103 2.50 0.03 0.145 2.921 0.002 0.016 2.50
1.50
2.00
2.25
2.50
3.000.12
13.30
25.00
33.33
20.00
30.000.162
4.124
11.046
14.900
13.677
13.54110.629
34.713
87.000
130.370
87.000
156.6000.009
0.344
1.150
1.939
1.438
3.1050.057
2.255
7.536
12.704
9.420
20.347
下载: 导出CSV
-
[1] 胡文瑞, 徐硕昌. 微重力流体力学. 北京: 科学出版社, 1999: 1-23Hu Wenrui, Xu Shuochang. Microgravity Fluid Mechanics. Beijing: Science Press, 1999: 1-23 (in Chinese) [2] Egry I, Herlach D, Ratke L. Properties and solidification of metallic melts under microgravity. International Foundry Research, 2009, 61(4): 30-41 [3] Perrot F, Guenoun P, Beysens D. Phase Separation of Binary Fluids Near a Critical Point Under Microgravity. Springer, 1988 [4] Antar BN, Ethridge EC, Maxwell D. Viscosity measurement using drop coalescence in microgravity. Microgravity - Science and Technology, 2003, 14(1): 9-19 doi: 10.1007/BF02873332 [5] Zhang T, Hu R, Zhang S, et al. Superfast growth dynamics of high-quality silicon nanowires on polymer films via self-selected laser-droplet-heating. Nano Letters, 2021, 21(1): 569-576 [6] Neilson GF, Weinberg MC. Outer space formation of a laser host glass. Journal of Non-Crystalline Solids, 1977, 23(1): 43-58 doi: 10.1016/0022-3093(77)90036-9 [7] Dietrich DL, Nayagam V, Hicks MC, et al. Droplet combustion experiments aboard the international space station. Microgravity Science and Technology, 2014, 26(2): 65-76 doi: 10.1007/s12217-014-9372-2 [8] Wang TG, Anilkumar AV, Lee CP. Oscillations of liquid drops: results from USML-1 experiments in space. Journal of Fluid Mechanics, 1996, 308: 1-14 [9] Young NO, Goldstein JS, Block MJ. The motion of bubbles in a vertical temperature gradient. Journal of Fluid Mechanics, 1959, 6(3): 350-356 doi: 10.1017/S0022112059000684 [10] Subramanian RS. Slow migration of a gas bubble in a thermal gradient. Aiche Journal, 2010, 27(4): 646-654 [11] Subramanian RS. Thermocapillary migration of bubbles and droplets. Advances in Space Research, 1983, 3(5): 145-153 doi: 10.1016/0273-1177(83)90239-9 [12] Balasubramaniam R, Chai AT. Thermocapillary migration of droplets: An exact solution for small Marangoni numbers. Journal of Colloid and Interface Science, 1987, 119(2): 531-538 doi: 10.1016/0021-9797(87)90300-6 [13] Barton KD, Subramanian RS. Thermocapillary migration of a liquid drop normal to a plane surface. Journal of Colloid and Interface Science, 1990, 137(1): 170-182 doi: 10.1016/0021-9797(90)90054-R [14] Keh HJ, Chen SH. The axisymmetric thermocapillary motion of two fluid droplets. International Journal of Multiphase Flow, 1990, 16(3): 515-527 doi: 10.1016/0301-9322(90)90079-X [15] Haj-Hariri H, Shi Q, Borhan A. Thermocapillary motion of deformable drops at finite Reynolds and Marangoni numbers. Physics of Fluids, 1997, 9(4): 845-855 doi: 10.1063/1.869182 [16] Yin Z, Chang L, Hu W, et al. Numerical simulations on thermocapillary migrations of nondeformable droplets with large Marangoni numbers. Physics of Fluids, 2012, 24(9): 092101 doi: 10.1063/1.4752028 [17] Brady PT, Herrmann M, Lopez JM. Confined thermocapillary motion of a three-dimensional deformable drop. Physics of Fluids, 2011, 23(2): 022101 doi: 10.1063/1.3529442 [18] Loewenberg M, Davis RH. Near-contact thermocapillary motion of two non-conducting drops. Journal of Fluid Mechanics, 1993, 256: 107-131 [19] Lavrenteva OM, Nir A. Axisymmetric thermal wake interaction of two drops in a gravity field at low Reynolds and high Peclet numbers. Physics of Fluids, 2003, 15(10): 3006-3014 doi: 10.1063/1.1605098 [20] Berejnov V, Lavrenteva OM, Nir A. Interaction of two deformable viscous drops under external temperature gradient. Journal of Colloid and Interface Science, 2001, 242(1): 202-213 doi: 10.1006/jcis.2001.7769 [21] Yin Z, Li Q. Thermocapillary migration and interaction of drops: two non-merging drops in an aligned arrangement. Journal of Fluid Mechanics, 2015, 766: 436-467 doi: 10.1017/jfm.2015.10 [22] Barton KD, Subramanian RS. The migration of liquid drops in a vertical temperature gradient. Journal of Colloid and Interface Science, 1989, 133(1): 211-222 doi: 10.1016/0021-9797(89)90294-4 [23] Hähnel M, Delitzsch V, Eckelmann H. The motion of droplets in a vertical temperature gradient. Physics of Fluids A: Fluid Dynamics, 1989, 1(9): 1460-1466 doi: 10.1063/1.857323 [24] Kang Q, Hu L, Huang C, et al. Experimental investigations on interaction of two drops by thermocapillary-buoyancy migration. International Journal of Heat and Mass Transfer, 2006, 49(15): 2636-2641 [25] Zhang ST, Duan L, Kang Q. Experimental research on thermocapillary migration of drops by using digital holographic interferometry. Experiments in Fluids, 2016, 57(7): 113 doi: 10.1007/s00348-016-2193-x [26] Zhang ST, Duan L, Kang Q. Experimental research on thermocapillary-buoyancy migration. Microgravity-Science and Technology, 2018, 30: 183-193 doi: 10.1007/s12217-017-9578-1 [27] Vincent M, Delville JP. Thermocapillary migration in small-scale temperature gradients: application to optofluidic drop dispensing. Physical Review E, 2012, 85: 026310 [28] 邓孺孺, 何颖清, 秦雁等. 近红外波段(900 ~ 2500 nm)水吸收系数测量. 遥感学报, 2012(1): 192-206 (Deng Ruru, He Yingqing, Qin Yan, et al. Measuring pure water absorption coefficient in the near-infrared spectrum (900 ~ 2500 nm). Journal of Remote Sensing, 2012(1): 192-206 (in Chinese) [29] 邓孺孺, 何颖清, 秦雁等. 分离悬浮质影响的光学波段(400 ~ 900 nm) 水吸收系数测量. 遥感学报, 2012(1): 174-191 (Deng Ruru, He Yingqing, Qin Yan, et al. Pure water absorption coefficient measurement after eliminating the impact of suspended substance in spectrum from 400 nm to 900 nm. Journal of Remote Sensing, 2012(1): 174-191 (in Chinese) -
下载:
点击查看大图
计量
- 文章访问数: 504
- HTML全文浏览量: 185
- PDF下载量: 74
- 被引次数: 0
