| Summary: | 碩士 === 國立臺灣大學 === 機械工程學研究所 === 93 === Mass transport induced by pulsatile electroosmotic flows in a two-dimensional microchannel is studied theoretically herein. With the assumptions of non-overlapping electrical double layers, linearized electrical potentials, streamwise fully-developed incompressible flows, and an infinitely dilute solution of neutral species, the governing equations for the electrical potential, the velocity field, and the species concentration distribution are solved analytically. The results indicate that the velocity and concentration distributions across the channel become more and more non-uniform as the Womersley number , or the oscillation frequency, increases. Results also reveal that, with a constant tidal displacement, the averaged mass transport rate increases with the Womersley number due to both the stronger convective and transverse dispersion effects. The averaged mass transport rate also increases with an increasing tidal displacement because of the associated stronger convective effects. The cross-over phenomenon of the mass transport rates for different species becomes possible with sufficiently large Debye lengths and at sufficiently high values of . As a result, with proper choices of the Debye length, oscillation frequency, and tidal displacement, pulsatile electroosmotic flow may become a good candidate for the first-step separation of the mass species.
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