Diffusioosmotic micropolar liquid flows in parallel plate microchannels subject to boundary slip

摘要

Analytical solutions to the microrotation, linear velocity, and volume flow rate are developed for electrokinetic diffusioosmotic flows of micropolar liquids in slit microchannel geometries subject to general slip boundary conditions. The macroscopic viscosity coefficients relevant to the micropolar fluid flow investigated herein are expressed as functions of the solid volume fraction to consistently reflect and better model the particle suspension microstructure of the micropolar liquid. Results obtained from systematic parametric analysis reveal that as compared to the Newtonian solutions, the forward or reversed diffusioosmotic micropolar velocity distributions as well as volume flow rates can be increased or decreased as the solid volume fraction is increased depending on the values of the microrotation boundary condition parameter and the boundary slip length. A crossover point can be defined to identify the value of the microrotation boundary condition parameter at which the flow rate magnitudes shift or change from a decreasing to an increasing dependence, or vice versa, on the increasing solid volume fraction. The value of this crossover point is increased with the introduction of finite slip lengths to the wall boundaries. Parametric regimes on the zeta potential versus diffusivity difference parameter map available for the volume flow rates to be directed towards upstream (downstream) are increased (decreased) by increasing either the solid volume fraction or the slip length, with the dependences on the solid volume fraction being diminished by introducing finite slip lengths or reducing the microrotation boundary condition parameter to zero.