Numerical Analysis of Passive Mixing Efficiency in a New Magneto-Electroosmotic Micromixer

Document Type : Original Article

Authors

1 Assistant Professor, Department of Mechanical Engineering, Technical and Vocational University (TVU), Tehran, Iran.

2 Professor, Department of Mechanical Engineering, University of Birjand, Birjand, Iran.

Abstract

In this paper, the mixing efficiency in a new magneto-electroosmotic micromixer has been numerically investigated and simulated. The micromixer in question is actually a microchannel with electroosmotic flow in which a permanent magnetic field perpendicular to the microchannel is used to create passive mixing. The main objective is to analyze the effects of magnetic flux density and zeta potential of the walls on the flow velocity field and ultimately the mixing efficiency. The flow geometry is a two-dimensional microchannel between two parallel plates, with uniformly charged surfaces throughout its walls. The flow is assumed to be incompressible, steady, and laminar. The governing equations, including the modified Navier–Stokes equations for fluid motion, the magnetic field equation, the equations for external and internal electric potentials, the Nernst–Planck equations for positive and negative ion concentration distributions, and the species concentration equation, are solved using the finite volume method. Numerical results showed that for microchannel flow at Reynolds number 0.03, electrical double layer parameter 16.42, and magnetic flux density of 5 N/A·m, an increase in zeta potential intensifies the flow in the central region of the microchannel, which leads to a significant decrease in mixing efficiency; from 98% to 45%. The results also showed that with increasing magnetic flux density, the mixing efficiency along the microchannel increases. This analysis can be effectively utilized in the design of microelectronic cooling systems and microchips.

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