Electroosmotic–peristaltic transport in microchannels: Critical reflux and flow reversal in biofluid dynamics

This paper considers the electroosmotic-modulated peristaltic motion of an electroconductive fluid through an axisymmetric microchannel with negatively charged flexible walls of uniform thickness. This study introduces a model for the electroosmotic augmented peristaltic flow, which is based on the conservation of mass and momentum, using the electroosmotic parameter, Helmholtz–Smoluchowski velocity, and arbitrary Reynolds number to capture the actual microscale transport phenomena at the biomedical level. The governing equations of motion arising from a perturbation approach for small amplitude ratio values are solved using a finite difference scheme. The graphical outputs and finite difference solutions are obtained using MATLAB. In this study, we analyze electroosmotic peristaltic flow under the condition of zero imposed pressure gradient at zeroth order, corresponding to the regime of free pumping. For the free pumping case, the time-mean axial velocity profiles are presented and analyzed for various values of electroosmotic parameter, Helmholtz–Smoluchowski velocity, and Reynolds number. The relation between the time-mean axial pressure gradient and the Reynolds number has been established. The values of the critical-reflux pressure gradient, critical-reflux electroosmotic velocity, and reversal flow phenomena are presented in this paper. These findings are particularly relevant for biofluid transport in microfluidic systems, such as artificial organs, lab-on-a-chip diagnostics, and drug delivery platforms, requiring precise, directional, and reversible flow control to simulate physiological transport processes effectively.