Browse > Article
http://dx.doi.org/10.3795/KSME-B.2015.39.7.579

Internal Flow and Evaporation Characteristic inside a Water Droplet on a Vertical Vibrating Hydrophobic Surface  

Kim, Hun (School of Mechanical Engineering, Pusan Nat'l Univ.)
Lim, Hee-Chang (School of Mechanical Engineering, Pusan Nat'l Univ.)
Publication Information
Transactions of the Korean Society of Mechanical Engineers B / v.39, no.7, 2015 , pp. 579-589 More about this Journal
Abstract
This study aims to understand the internal flow and the evaporation characteristics of a deionized water droplet subjected to vertical forced vibrations. To predict and evaluate its resonance frequency, the theories of Lamb, Strani, and Sabetta have been applied. To visualize the precise mode, shape, and internal flow inside a droplet, the experiment utilizes a combination of a high-speed camera, macro lens, and continuous laser. As a result, a water droplet on a hydrophobic surface has its typical shape at each mode, and complicated vortices are observed inside the droplet. In particular, large symmetrical flow streams are generated along the vertical axis at each mode, with a large circulating movement from the bottom to the top and then to the triple contact line along the droplet surface. In addition, a bifurcation-shaped flow pattern is formed at modes 2 and 4, whereas a large ellipsoid-shape flow pattern forms at modes 6 and 8. Mode 4 has the fastest internal flow speed and evaporation rate, followed by modes 8 then 6, with 2 having the slowest of these properties. Each mode has the fastest evaporation rate amongst its neighboring frequencies. Finally, the droplet evaporation under vertical vibration would lead to more rapid evaporation, particularly for mode 4.
Keywords
Hydrophobic Surface; Contact Radius; Equilibrium Contact Angle; Flow Visualization; Natural Frequency; Resonance Frequency; Lobe;
Citations & Related Records
연도 인용수 순위
  • Reference
1 Kelvin, 1890, Mathematical and Physical Papers, Vol. 3, Clay, pp. 384.
2 Rayleigh, L., 1894, The Theory of Sound, Macmillan, New York.
3 Lamb, H., 1932, Hydrodynamics, Cambridge Univ. Press, New York, pp. 475.
4 Strani, M., and Sabetta, F., 1984, "Free Vibrations of a Drop in Partial Contact with a Solid Support," J. Fluid. Mech, Vol. 141, pp. 233-247.   DOI   ScienceOn
5 Daniel, S., Sircar, S., Gliem, J. and chaudhury, M. K., 2004, "Ratcheting Motion of Liquid Drops on Gradient Surfaces," Langmuir, Vol. 20, pp. 4085-4098.   DOI   ScienceOn
6 Daniel, S., Chaudhury, M. K. and De Gennes, P. G., 2005, "Vibration-actuated Drop Motion on Surfaces for Batch Microfluidic Processes," Langmuir, Vol. 21, pp. 4240-4248.   DOI   ScienceOn
7 Dong, L., Chaudhury, A. and Chaudhury, M. K., 2006, "Lateral Vibration of a Water Drop and its Motion on a Vibrating Surface," Eur. Phys. J. E, Vol. 21, pp. 231-242.   DOI
8 Noblin, X., Buguin, A. and Brochard-Wyart, F., 2009, "Vibration of Sessile Drops," Eur. Phys. J. Special Topics, Vol. 166, pp. 7-10.   DOI
9 Brunet, P., Eggers, J. and Deegan, R. D., 2009, "Motion of a Drop Driven by Substrate Vibrations," Eur. Phys. J. Special Topics, Vol 166, pp. 11-14.   DOI
10 McHale, G., Elliott, S. J., Newton, M. I., Herbertson, D. L. and Esmer, K., 2009, "Levitation-Free Vibrated Droplets: Resonant Oscillations of Liquid Marbles," Langmuir, Vol. 25, pp. 529-533.   DOI   ScienceOn
11 Hong, F. J., Jiang, D. D. and Cheng, P., 2012, "Frequency-dependent Resonance and Asymmetric Droplet Oscillation under ac Electrowetting on Coplanar Electrodes," J. Micromech. Microeng, Vol. 22, pp. 1-9.
12 Oh, J. M., Ko, S. H. and Kang, K. H., 2008, "Shape Oscillation of a Drop in AC Electrowetting," Langmuir, Vol. 24, pp. 8379-8386.   DOI   ScienceOn
13 Wachters L. and Westerling N., 1966, "The Heat Transfer from a Hot Wall to Impinging Water Drops in the Spheroidal State," Chem. Eng. Sci. Vol. 21, pp. 1181.
14 Depaoli, D. W., Feng, J. Q., Basaran, O. A. and Scott, T. C., 1995, "Hysteresis in forced Oscillations of Pendant Drops," Phys. Fluids, Vol. 7, pp. 1181-1183.   DOI   ScienceOn
15 Wilkes, E. D. and Basaran, O. A., 1997, "Forced Oscillations of Pendant (Sessile) Drops," Phys. Fluids, Vol. 9, pp. 1512-1528.   DOI   ScienceOn
16 Kim, H. Y., 2004, "Drop Fall-off from the Vibrating Ceiling," Phys. Fluids, Vol. 14, pp. 474.
17 Brunet, P., Eggers, J. and Deegan, R. D., 2007, "Vibration-Induced Climbing of Drops," Phys. Rev. Lett, Vol. 99, pp. 144501-1-4.   DOI   ScienceOn
18 Matsumoto, T., Fujii, H., Ueda, T., Kamai, M. and Nogi, K., 2005, "Measurement of Surface Tension of Molten Copper using the Free-fall Oscillating Drop Method," Meas. Sci. Technol, Vol. 16, pp. 432-437.   DOI   ScienceOn
19 Yamakita, S., Matsui, Y. and Shiokawa, S., 1999, "New Method for Measurement of Contact Angle (Droplet Free Vibration Frequency Method)," Jpn. J. Appl. Phys, Vol. 38, pp. 3127-3130.   DOI
20 Makino, K. and Michiyosi, I., "The Behavior of a Water Droplet on Heated Surfaces," Int. J. Heat Transfer, Vol. 27, pp. 781-791.
21 Scriven, L. E. and Sternling, C. V., 1960, "The Marangoni Effects" Nature, Vol. 187, pp. 186-188.   DOI
22 Hu, H. and Larson, R.G., 2006, "Marangoni Effect Reverses Coffee-Ring Depositions," J. Phys. Chem. B, Vol. 110, pp. 7090-7094.   DOI   ScienceOn
23 Oh, J. M., Legendre, D. and Mugele, F., 2012, "Shaken not Stirred On Internal - Flow Patterns in Oscillating Sessile Drops," Europhysics Letters, Vol. 98, pp. 34003.   DOI   ScienceOn
24 Xu, X. F. and Luo, J. b., 2007, "Marangoni Flow in an Evaporating Water Droplet," Appl. Phys. Letter, Vol. 91, pp. 124102.   DOI   ScienceOn
25 Wang, H. T., Wang, Zh. B., Huang, L. M., Mitra, A. and Yan, Y. S., 2001, "Surface Patterned Porous Films by Convection-Assisted Dynamic Self-Assembly of Zeolite Nanoparticles," Langmuir, Vol. 17, pp. 2572-2574.   DOI   ScienceOn
26 Truskett, V. and Stebe, K. j., 2003, "Influence of Surfactants on an Evaporating Drop: Fluorescence Images and Particle Deposition Patterns," Langmuir, Vol. 19, pp. 8271-8279.   DOI   ScienceOn
27 Lee, S. M. and Kang, I. S., 1999, "Three-dimensional Analysis of the Steady-state Shape and Small-amplitude Oscillation of a Bubble in Uniform and Non-uniform Electric Fields," J. Fluid. Mech, Vol. 384, pp. 59-91.   DOI   ScienceOn
28 Oh, J. M., Kim, P. J. and Kang, I. S., 2001, "Chaotic Oscillation of a Bubble in a Weakly Viscous Dielectric Fluid under Electric Fields," Phys. Fluids, Vol. 13, No. 10, pp. 2820-2830.   DOI   ScienceOn
29 Kang, K. H., Lee, S. J., Lee, C. M. and Kang, I. S., 2004, "Quantitative Visualization of Flow Inside an Evaporating Droplet using the Ray Tracing Method," Meas. Sci. Technol., Vol. 15, pp. 1104-1112.   DOI   ScienceOn
30 Picknett, R. G. and Bexon, R., 1976, "The Evaporation of Sessile or Pendant Drops in Still Air," Journal of colloid and Interface Science, Vol. 61, No. 2, pp. 336-350.   DOI