Document Type: Original Article


1 Department of Mechanical Engineering, University of Birjand, Birjand, Iran

2 Department of Mechanical Engineering, University of Zabol, Zabol, Iran


Objective: In this article, a numerical study is conducted on mixing of two fluids in the liquid phase with two different concentrations of a chemical species in the electro-osmotic flow. Methods: The base liquid is an electrolyte which flows in a two-dimensional micro-channel having electrically charged walls. Lorentz electric force, which is used as stimulating flow factor, is created by applying an external electric field on the electric double layer (EDL) aroused by adjacency of electrolyte and charged wall. Results: To ensure the convergence of the results obtained from the computer program, equations are solved iteratively until the residual amount after solving each equation is less than machine error and independence of results from the number and location of network nodes is verified for an experimental flow. To increase the mixing efficiency, some square and triangle shaped obstacles are embedded on the micro channel wall. Herein, the fundamental principles for passive mixing as well as the effect of frequency and height of the barriers on mixing efficiency are studied. The obtained results from numerical solving of electro-osmotic flow in micro-channel are compared with the theoretical results and a very good agreement is observed.


Main Subjects

Hessel,V., Lˆwe, H., Schˆnfeld, F., "Micromixers a review on passive and active mixing principles", Chemical Engineering Science, vol 60 , pp 2479 ñ 2501, 2004.
Lin, Y., Gerfen, G. J., Rousseau, D. L., Yeh, S. R., "Ultrafast microfluidic mixer and freezeñquenching device", Analytical Chemistry ,75, pp 5381ñ5386, 2003.
Kumar, V., Paraschivoiu, M., Nigam, K. D. P., "Single-phase fluid flow and mixing in microchannels", Journal of Chemical Engineering Science ,Article in Press, 2010.
Che, C. K., Chao, C., "Electrokinetically-driven flow mixing in microchannels with wavy surface", Journal of Colloid and Interface Science 312, pp 470ñ80, 2007.
Wang, D., Summers, J. L., Gaskell, P. H., "Modelling of electrokinetically driven mixing flow in microchannels with patterned blocks", Computers and Mathematics with Applications ,55 , pp 1601ñ1610, 2008.
A.M. Afonso, M.A. Alves, F.T. Pinho, " Analytical solution of two-fluid electro-osmotic flows of viscoelastic fluids", Journal of Colloid and Interface Science 395, pp. 277ñ 286, 2013
Xiao-Xia Li, Ze Yin, Yong-Jun Jian, Long Chang, Jie Su, Quan-Sheng Liu, " Transient electro-osmotic flow of generalized Maxwell fluids through a microchannel" , Journal of Non-Newtonian Fluid Mechanics 187ñ188, pp.
43-47, 2012.
A.M. Afonso, M.A. Alves, F.T. Pinho, " Analytical solution of mixed electro-osmotic/pressure driven flows of viscoelastic fluids in microchannels" , Journal of NonNewtonian Fluid Mechanics 159, pp. 50-63, 2009.
Mirbozorgi, S. A., Niazmand, H., Renksizbulut, M., "Electro-Osmotic Flow in Reservoir Connected Flat Microchannels With Non-Uniform Zeta Potential",
Journal of Fluids Engineering 128 , pp 1133ñ43, 2006.
Ghia, U., Ghia, K. N., Shin, C. T., "High-Re solutions for incompressible flow using the NavierñStokes equations and a multigrid method", Journal of Computational Physics; 48, pp 387ñ411, 1982.