Library Subscription: Guest
Begell Digital Portal Begell Digital Library eBooks Journals References & Proceedings Research Collections
Multiphase Science and Technology
SJR: 0.183 SNIP: 0.483 CiteScore™: 0.5

ISSN Print: 0276-1459
ISSN Online: 1943-6181

Multiphase Science and Technology

DOI: 10.1615/MultScienTechn.2019031133
pages 287-303


Kalichetty Srinivasa Sagar
Department of Mechanical Engineering, IIT Madras, Chennai, India
K. G. Dwaraknath
Department of Mechanical Engineering, IIT Madras, Chennai, India
Arvind Pattamatta
Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai–600036, India
Thirumalachari Sundararajan
Thermodynamics and Combustion Engineering Laboratory Department of Mechanical Engineering Indian Institute of Technology Madras, Chennai – 600036, India


The dynamics of a liquid plug actuated due to the thermocapillary phenomenon in a capillary tube is studied in the present work. A plug in a capillary tube forms two menisci. When the temperature is increased at one end of the plug, the surface tension decreases at that corresponding meniscus. The reduced surface tension induces a capillary pressure difference causing motion of the plug. The velocity accelerates to a peak and then decelerates to a creeping velocity. A theoretical model is developed based on the balance of surface tension, viscous and inertial forces. The prediction of migration dynamics by the model agrees well with the experiments. The effect of the length of the plug, heat flux applied to the heater, and viscosity of silicone oil on migration dynamics is studied experimentally. The heat flux augments the migration phenomenon; whereas, the length and viscosity depreciate it. The reasons for various migration characteristics are explained. The predictions of the magnitude of peak velocity made by the theory across the change of parameters also agree well with the experimental observations. The model is then used to study the effect of radius and thermal conductivity of the capillary tube on the migration phenomenon. It is observed that the radius has proportional dependence on the magnitude of peak velocity; whereas, the thermal conductivity has a nonmonotonic dependence. The understanding developed from this work finds applications in the various fields of droplet's science and especially in the area of microfluidics.


  1. Bico, J. and Quere, D., Note: Falling Slugs, J. ColloidInterf. Sci., vol. 243, no. 1, pp. 262-264,2001.

  2. Bradley, A.T., Box, F., Hewitt, I.J., and Vella, D., Wettability-Independent Droplet Transport by Bendotaxis, Phys. Rev. Lett., vol. 122, no. 7, p. 074503,2019.

  3. Bretherton, F.P., The Motion of Long Bubbles in Tubes, J. Fluid Mech., vol. 10, no. 2, p. 166-188, 1961.

  4. Brzoska, J.B., Brochard-Wyart, F., and Rondelez, F., Motions of Droplets on Hydrophobic Model Surfaces Induced by Thermal Gradients, Langmuir, vol. 9, pp. 2220-2224, 1993.

  5. Burns, M.A., Mastrangelo, C.H., Sammarco, T.S., Man, F.P., Webster, J.R., Johnsons, B.N., Foerster, B., Jones, D., Fields, Y., Kaiser, A.R., and Burke, D.T., Microfabricated Structures for Integrated DNA Analysis, Proc. Nat. Acad. Sci. USA, vol. 93, no. 11, pp. 5556-5561,1996.

  6. Glockner, P.S. and Naterer, G.F., Surface Tension and Frictional Resistance of Thermocapillary Pumping in a Closed Microchannel, Int. J. Heat Mass Transf., vol. 49, nos. 23-24, pp. 4424-4436, 2006.

  7. Irajizad, P., Ray, S., Farokhnia, N., Hasnain, M., Baldelli, S., and Ghasemi, H., Remote Droplet Manipulation on Self-Healing Thermally Activated Magnetic Slippery Surfaces, Adv. Mater. Interf., vol. 4, no. 12, pp. 1-7,2017.

  8. Ito, Y., Heydari, M., Hashimoto, A., Konno, T., Hirasawa, A., Hori, S., Kurita, K., and Nakajima, A., The Movement of a Water Droplet on a Gradient Surface Prepared by Photodegradation, Langmuir, vol. 23, no. 4, pp. 1845-1850,2007.

  9. Jiao, Z. and Nguyen, N.T., Thermocapillary Pumping, Encyclopedia of Microfluidics and Nanofluidics, New York: Springer Science and Business Media, pp. 3267-3271,2015.

  10. Jiao, Z., Nguyen, N.T., and Huang, X., Thermocapillary Actuation of a Water Droplet Encapsulated in an Oil Plug, J. Micromech. Microeng., vol. 17, no. 9, pp. 1843-1852, 2007a.

  11. Jiao, Z., Nguyen, N.T., and Huang, X., Thermocapillary Actuation of Liquid Plugs Using a Heater Array, Sensors Actuators, vol. 140, no. 2, pp. 145-155, 2007b.

  12. Karbalaei, A., Kumar, R., and Cho, H.J., Thermocapillarity in Microfluidics-A Review, Micromachines, vol. 7, no. 1,pp. 1-41,2016.

  13. Khalil, K.S., Mahmoudi, S.R., Abu-Dheir, N., and Varanasi, K.K., Active Surfaces: Ferrofluid-Impregnated Surfaces for Active Manipulation of Droplets, Appl. Phys. Lett., vol. 105, no. 4, p. 41604, 2014.

  14. Kim, H.Y., On Thermocapillary Propulsion ofMicroliquid Slug, Nanoscale Microscale Thermophys. Eng., vol. 7265, pp. 351-362, 2008.

  15. Le, T.L., Chen, J.C., Hwu, F.S., and Nguyen, H.B., Numerical Study of the Migration of a Silicone Plug inside a Capillary Tube Subjected to an Unsteady Wall Temperature Gradient, Int. J. Heat Mass Transf, vol. 97, pp. 439-449,2016.

  16. Nelson, W.C. and Kim, C.J.C., Droplet Actuation by Electrowetting-On-Dielectric (EWOD): A Review, J. Adhesion Sci. Technol, vol. 26, nos. 12-17, pp. 1747-1771,2012.

  17. Nguyen, N.T. and Huang, X., Thermocapillary Effect of a Liquid Plug in Transient Temperature Fields, Jap. J. Appl. Phys, vol. 44, no. 2, pp. 1139-1142, 2005.

  18. Saien, J. and Akbari, S., Interfacial Tension of Toluene+ Water+ Sodium Dodecyl Sulfate from (20 to 50) C and PH between 4 and 9, J. Chem. Eng. Data, vol. 51, no. 5, pp. 1832-1835, 2006.

  19. Sammarco, T.S. and Burns, M.A., Thermocapillary Pumping of Discrete Drops in Microfabricated Analysis Devices, AIChEJ., vol. 45, no. 2, pp. 350-366,1999.

  20. Subramanian, R.S. and Balasubramaniam, R., The Motion of Bubbles and Drops in Reduced Gravity, Cambridge, U.K., 2001.

  21. Szymczyk, J. and Siekmann, J., Numerical Calculation of the Thermocapillary Motion of a Bubble under Microgravity, Chem. Eng. Commun., vol. 69, no. 1, pp. 129-147, 1988.

  22. Tanner, L.H., The Spreading of Silicone Oil on Horizontal Surfaces, J. Phys. D, vol. 12, no. 1838, pp. 1473-1485, 1979.

  23. Teh, S.Y., Lin, R., Hung, L.H., and Lee, A.P., Droplet Microfluidics, Lab Chip, vol. 8, no. 2, pp. 198-220, 2008.

  24. Wehking, J.D. and Kumar, R., Droplet Actuation in an Electrified Microfluidic Network, Lab Chip, vol. 15, pp. 793-801,2015.

  25. Yang, Y., Odukoya, A., and Naterer, G.F., Droplet Meniscus Motion of Thermocapillary Pumping in a Closed Microchannel with External Heating, 2010 12th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, ITherm 2010, IEEE, Piscataway, NJ, pp. 1-6, 2010.

  26. Young, N., Goldstein, J., and Block, M.J., The Motion of Bubbles in a Vertical Temperature Gradient, J. FluidMech, vol. 6, no. 3, pp. 350-356, 1959.

Articles with similar content:

Heat Pipe Science and Technology, An International Journal, Vol.3, 2012, issue 2-4
Sameer Khandekar, Ashish Kumar Bajpai
Effect of Velocity and Evaporation on Non-IsoThermal Meniscus in a Capillary
International Heat Transfer Conference 15, Vol.31, 2014, issue
Adel M. Benselama, Yves Bertin, Antoine Voirand
International Heat Transfer Conference 9, Vol.3, 1990, issue
T. Fukano, Chang-Lin Tien, K. Kadoguchi
Annual Review of Heat Transfer, Vol.14, 2005, issue 14
Ravi Prasher, Prajesh Bhattacharya, Patrick E. Phelan
Proceedings of Symposium on Energy Engineering in the 21st Century (SEE2000) Volume I-IV, Vol.0, 2000, issue
T. S. Zhao, Q. C. Bi