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Research Papers: Flows in Complex Systems

# On the Modeling and Simulation of Ion Drag Electrohydrodynamic Micropumps

[+] Author and Article Information
S. Mohammed Hasnain, Akhilesh Bakshi, P. Ravi Selvaganapathy

Department of Mechanical Engineering McMaster University Hamilton, ON, Canada, L8S 4L7

Chan Y. Ching1

Department of Mechanical Engineering McMaster University Hamilton, ON, Canada, L8S 4L7chingcy@mcmaster.ca

1

Corresponding author.

J. Fluids Eng 133(5), 051102 (May 31, 2011) (7 pages) doi:10.1115/1.4004024 History: Received August 19, 2010; Revised April 12, 2011; Published May 31, 2011; Online May 31, 2011

## Abstract

A numerical model for ion-drag electrohydrodynamic (EHD) micropumps has been developed. The Poisson and charge conservation equations are solved to determine the electric body force within the flow domain. The charge distribution at the electrodes is assumed to depend on the magnitude and the gradient of the electric field at the surface of the electrode. The flow field is then determined by solving the momentum equation with the inclusion of the electric body force. Simulations were performed for micropump configurations that consisted of a series of planar electrode pairs embedded along the bottom wall of a microchannel. A two-dimensional segment of the channel with a single electrode pair is simulated using periodic boundary conditions at the inlet and outlet for the charge and electric fields. An empirical model was developed to estimate the charge boundary condition for the simulations. The simulation results were in good agreement with existing experimental data. The model was then used to perform a parametric study of the effect of channel height on the pump performance.

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## Figures

Figure 1

Schematic of typical EHD micropump showing electrode geometry

Figure 2

Cross section of microchannel with one pair of planar symmetric electrodes

Figure 3

Variation of local charge density along the surface of the emitter electrode (assuming charge proportional to the gradient of the electric field at the surface) for S-80 at an applied voltage of 600 V

Figure 4

Variation of pressure along the electrode pair stages for S-80 micropump at an applied voltage of 400 V

Figure 5

Contour plots for (a) electric field, (b) charge density, and (c) flow field for S-80 at an applied voltage of 600 V

Figure 6

Comparison of simulation results for pressure generation (□) with experimental results (○) of Kazemi [12] for (a) S-80, (b) S-120

Figure 7

Pressure-flow rate characteristics for (a) S-80 at □ 600 V, ○ 700 V, and Δ 800 V; and (b) S-120 at □ 800 V, ○ 900 V, and Δ 1000 V

Figure 8

Comparison between local charge density assumed proportional to the gradient of the electric field (○) and predicted values from correlation (□) for S-80 at an applied voltage of 600 V for (a) left end and (b) right end of the emitter

Figure 9

Comparison of predicted current (□) with experimental current (○) of Kazemi [12] for (a) S-80, (b) S-120

Figure 10

Pressure-flow rate characteristics for microchannel height of □ 75, ○ 100, and Δ 125 microns for pump configuration (a) S-80 at 600 V, (b) S120 at 800 V

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