Electroosmotic Flow in Microchannels

Lesani, Mostafa | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 42090 (58)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Saeedi, Mohammad Saeed
  7. Abstract:
  8. The present study examines both Direct Current (DC) and Alternating Current (AC) electroosmotic flows in a parallel plate microchannel. The method consists of a central finite difference scheme for spatial terms and a forward difference scheme for the temporal term. Asymmetric boundary conditions are assumed for Poison-Boltzmann equation used to determine the electric double layer (EDL) potential distribution. The potential distribution is then used to evaluate the velocity distribution for both DC and AC electroosmotic flows. The velocity distributions are obtained by applying slip boundary conditions on the walls to account for probable hydrophobicity of the surfaces. After determining the velocity distributions numerically, the energy equation is solved by taking into account the effects of viscous dissipation and non-uniform Joule heating. The results reveal that, for the majority of the practical applications, the Debye-Hückel linearization may be used to evaluate the velocity distribution, provided that the dimensionless Debye-Hückel parameter is higher than 50. Also, the effect of increasing zeta potential is to increase the mean velocity. The effects of increasing the dimensionless Debye-Hückel parameter and the dimensionless zeta potential are found to be increasing the Poiseuille number, whereas the effect of increasing the Knudsen number is to decrease the Poiseuille number. For AC electroosmosis, the effect of increasing the Knudsen number is to slightly increase the dimensionless temperature profile. Furthermore, the effect of increasing the dimensionless time is to increase the dimensionless oscillatory temperature until a steady oscillatory condition is achieved
  9. Keywords:
  10. Microchannel ; Zeta Potential ; Knudsen Number ; Electroosmotic Flow ; Joul Heating

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