Abstract
In this paper, a “macroscopic-scale” numerical method for drop oscillation in AC electrowetting is presented. The method is based on a high-fidelity moving mesh interface tracking (MMIT) approach and a “microscopic model” for the moving contact line. The contact line model developed by Ren et al. [Phys Fluids, 2010, 22: 102103] is used in the simulation. To determine the slip length in this model, we propose a calibration procedure using the experimental data of drop spreading in DC electrowetting. In the simulation, the frequency of input AC voltage varies in a certain range while the root-mean-square value remains fixed. The numerical simulation is validated against the experiment and it shows that the predicted resonance frequencies for different oscillation modes agree reasonably well with the experiment. The origins of discrepancy between simulation and experiment are analyzed in the paper. Further investigation is also conducted by including the contact angle hysteresis into the contact line model to account for the “stick-slip” behavior. A noticeable improvement on the prediction of resonance frequencies is achieved by using the hysteresis model.
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References
Kang K H. How electrostatic fields change contact angle in electrowetting. Langmuir, 2002, 18: 10318–10322
Mugele F, Baret J C. Electrowetting: From basics to applications. J Phys-Condens Matter, 2005, 17: 705–774
Pollack MG, Fair R B, Shenderov A D. Electrowetting-based actuation of liquid droplets for microfluidic applications. Appl Phys Lett, 2000, 77: 1725–1726
Pollack MG, Shenderov A D, Fair R B. Electrowetting-based actuation of droplets for integrated microfluidics. Lab Chip, 2002, 2: 96–101
Hayes R A, Feenstra B J. Video-speed electronic paper based on electrowetting. Nature, 2003, 425: 383–385
Krupenkin T, Yang S, Mach P. Tunable liquid microlens. Appl Phys Lett, 2003, 82: 316–318
Huh D, Tkaczyk A H, Bahng J H. Reversible switching of high-speed air-liquid two-phase flows using electrowetting-assisted flow pattern change. J Am Chem Soc, 2003, 125: 14678–14679
Sen P, Kim C J. A fast liquid-metal droplet microswitch using EWODdriven contact-line sliding. J Microelectromech S, 2009, 18: 174–185
Oh J M, Ko S H, Kang K H. Shape oscillation of a drop in ac electrowetting. Langmuir, 2008, 24: 8379–8386
Oh J M, Ko S H, Kang K H. Analysis of electrowetting-driven spreading of a drop in air. Phys Fluids, 2010, 22: 032002
Sen P, Kim C J. Capillary spreading dynamics of electrowetted sessile droplets in air. Langmuir, 2009, 25: 4302–4305
Decamps C, Coninck J D. Dynamcis of spontaneous spreading under electrowetting conditions. Langmuir, 2000, 16: 10150–10153
Ko S H, Lee H, Kang K H. Hydrodynamic flows in electrowetting. Langmuir, 2008, 24: 1094–1101
Garcia-Sanchez P, Ramos A, Mugele F. Electrothermally driven flows in ac electrowetting. Phys Rev E, 2010, 81: 0153039 (R)
Lee H, Yun S, Ko S H. An electrohydrodynamic flow in ac electrowetting. Biomicrofluidics, 2009, 3: 044113
Baret J C, Decre M M J, Mugele F. Transport dynamics in open microfluidic grooves. Langmuir, 2007, 23: 5200–5204
Cooney C G, Chen C Y, Emerling M R, et al. Electrowetting droplet microfluidics on a single planar surface. Microfluid Nanofluid, 2006, 2: 435–446
Chung S K, Zhao Y, Yi U C, Separation and collection of microparticles using oscillating bubbles. In: the 20th International Conference on Micro Electro Mechanical Systems. Hyogo: IEEE, 2007. 21–25
Gunji M, Washizu M J. Self-propulsion of a water droplet in an electric field. J Phys D-Appl Phys, 2005, 38: 2417–2423
Mugele F, Baret J C, Steinhauser D. Microfluidic mixing through electrowetting-induced droplet oscillations. Appl Phys Lett, 2006, 88: 204106
Blake T D, Clarke A, Stattersfield E H. An investigation of electrostatic assist in dynamic wetting. Langmuir, 2000, 16: 2928–2935
Gabay C, Berge B, Dovillaire G, et al. Dynamic study of a varioptic variable focal lens. Proc SPIE, 2002, 4767: 159–165
Rayleigh L. On the capillary phenomena of jets. Proc R Soc London, 1879, 29: 71–79
Lamb H. Hydrodynamics. 6th ed. Cambridge: Cambridge University Press, 1932
Strani M, Sabetta F. Free vibrations of a drop in partial contact with a solid support. J Fluid Mech, 1984, 141: 233–247
Noblin X, Buguin A, Brochard-Wyart F. Self-propulsion of a water droplet in an electric field. Eur Phys J E, 2004, 14: 395–404
Noblin X, Buguin A, Brochard-Wyart F. Triplon modes of puddles. Phys Rev Lett, 2005, 94: 166102
Dong L, Chaudhury A, Chaudhury M K. Lateral vibration of a water drop and its motion on a vibrating surface. Eur Phys J E, 2006, 21: 231–242
Fayzrakhmanova I S, Straube A V. Stick-slip dynamics of an oscillated sessile drop. Phys Fluids, 2009, 21: 072104
Dupont J B, Legendre D. Numerical simulation of static and sliding drop with contact angle hysteresis. J Comput Phys, 2010, 229: 2453–2478
Li Z L, Lai M C, He GW, et al. An augmented method for free boundary problems with moving contact lines. Comput Fluids, 2010, 39: 1033–1040
Hong F J, Cheng P, Sun Z, et al. Simulation of spreading dynamics of a EWOD droplet with dynamic contact angle and contact angle hysteresis. In: Proceedings of the ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer, 2009. MNHMT 2009-18558: 635–641
Perot B, Nallapati R. A moving unstructured staggered mesh method for the simulation of incompressible free-surface flows. J Comput Phys, 2003, 184: 192–214
Chang W, Giraldo F, Perot B. Analysis of an exact fractional step method. J Comput Phys, 2002, 180: 183–199
Dai M Z, Wang H, Perot B, et al. Direct interface tracking of droplet deformation. Atomiz Spr, 2002, 12: 721–736
Dai M Z, Schmidt D P. Adaptive tetrahedral meshing in free-surface flow. J Comput Phys, 2005, 208: 228–252
Quan S P, Schmidt D P. A moving mesh interface tracking method for 3D incompressible two-phase flows. J Comput Phys, 2007, 221: 761–780
Anderson D M, McFadden G B, Wheeler A A. Diffusive-interface method in fluid mechanics. Annu Rev Fluid Mech, 1998, 30: 139–165
Dussan E B. On the shredding of liquids on solid surfaces: Static and dynamic contact lines. Annu Rev Fluid Mech, 1979, 11: 371–400
Ren W, EW. Boundary conditions for the moving contact line problem. Phys Fluids, 2007, 19: 022101
Ren W, Hu D, E W. Continuum models for the contact line problem. Phys Fluids, 2010, 22: 102103
Lavi B, Marmur A. The exponential power law: Partial wetting kinetics and dynamic contact angles. Colloid Surf A, 2004, 250: 409–414
Walker SW, Shapiro B, Nochetto R H. Electrowetting with contact line pinning: Computational modeling and comparisons with experiments. Phys Fluids, 2009, 21: 102103
Tanner L H. The spreading of silicone oil drops on horizontal surfaces. J Phys D-Appl Phys, 1979, 12: 1473–1484
De Gennes P G, Hua X, Levinson P. Dynamics of wetting: Local contact angles. J Fluid Mech, 1990, 212: 55–63
Cox R G. Inertial and viscous effects on dynamic contact angles. J Fluid Mech, 1998, 357: 249–278
Eggers J. Toward a description of contact line motion at higher capillary numbers. Phys Fluids, 2004, 16: 3491–3494
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Li, X., He, G. & Zhang, X. Numerical simulation of drop oscillation in AC electrowetting. Sci. China Phys. Mech. Astron. 56, 383–394 (2013). https://doi.org/10.1007/s11433-012-4986-0
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DOI: https://doi.org/10.1007/s11433-012-4986-0