Effect of Electric Field Mediated Fluid Thickening on Electrokinetics over Charge - Modulated Interfaces

We develop a model to describe ion transport , in micro- and nanochannels with variable surface charge, taking into account electric- field mediated fluid thickening ( viscoelectric effect). In our cross- sectionally averaged model, the effects of electric double layer on the axial transport are taken into account via modifications in the classical Poisson- Boltzmann theory. The effect of viscoelectricity is taken into account for different characteristic length scales of the EDL resulting in distinctive features for overlapped and non- overlapped EDLs. We also consider the effect of the axial pitch of surface charge modulation on the concentration profiles along the central axis of the channel. We relate our findings on the effect of heterogeneous surface charge on the velocity profile on the fluidic confinement. We also calculate the induced pressure gradient from the force balance considerations. On comparing the induced pressure gradient for flows with and without viscoelectric effect, our results reveal that the induced pressure gradient is more for the former, deciphering- unravelled interplay of electromechanical and hydrodynamics over charge- modulated interfaces.