Electroosmotic magnetohydrodynamics-driven solute dispersion in couple stress fluid flow through microchannel: Effect of transverse electric field

This article investigated the solute dispersion process in a magnetohydrodynamic electroosmotic flow of couple stress fluid in a parallel-plate microchannel. A heterogeneous first-order boundary reaction is applied along the plates with an electric field in axial and lateral (transverse) directions. The finite difference scheme is used to solve moment equations obtained through Aris's method of moments. Using Gill's series expansion method, two-dimensional concentration profiles in the microfluidic system are obtained and depicted in three-dimensional graphs. The results from the study indicate that a smaller γ (couple stress parameter) increases flow resistance due to stronger intermolecular attraction between mobile ions, while a larger γ weakens these forces, altering flow patterns and enhancing fluid mixing and particle dispersion. In addition, they exhibit a uniform distribution of oscillations and a stabilized pattern at extensive time intervals. At the diffusive dispersion combined flow regimes, for small electroosmotic flow (K), a roughness is noticed in the mean concentration peak because of low mixing. Eventually, as it increases, the peak becomes smooth and shifts to the right of the axial direction. In combined flow in the absence of the electroosmotic effect, the dispersion coefficient (Dac) has periodic peaks with a maximum value around 2 ×10−3, while in the existence of electroosmotic effect hikes the oscillations of dispersion coefficient (Dac) with maximum value about 16 ×10−3. This study gives a complex mechanism for controlling solute dispersion through the microfluidic system, which has enormous applications in drug delivery, oil refining, cell separation, dialysis systems, diagnostics, etc.