Electroosmotic flow of Bingham plastic ionic liquids driven by peristaltic pumping

Abstract

An analytical study for electroosmotic flow of Bingham plastic ionic liquids driven by peristaltic pumping through a microchannel is investigated. The Poisson-Boltzmann equation for electric potential distribution is implemented to accommodate the electrical double layer in the microchannel. Boundary layer flow model is simplified under the low Reynolds number and long wavelength approximations. The solution of the electrical potential is based on the Debye- Hückel approximation for a symmetric (Z: Z) electrolyte solution. Closed form solutions for axial velocity, pressure gradient, pressure rise along one wavelength and stream function are derived. To examine the influence of physical parameters like Bingham plug flow width, electroosmotic parameter and Helmholtz-Smoluchowski velocity on pumping characteristics, computational results are illustrated. With vanishing yield stress, the Newtonian case is retrieved. An increase in plug flow width is observed to decrease volumetric flow rate and has a varied influence on the pressure rise depending on whether the flow is in the free pumping or pumping region. The findings of this study may useful in designing the microfluidics peristaltic pumps which often required to minimize the circulating volume of fluid and also helping to integrate the micropumping structure into the microfluidics circuit.