Mass Transport of Combined Oscillating Electroosmotic and Pressure Driven Flow Through Cylindrical Nanopore Considering Ion Partitioning Effects

In this study, an electroneutral solute of a Newtonian fluid is theoretically analysed as it passes through a nanopore coated with a polyelectrolyte layer under the regulation of an alternating current electric field and pressure gradient. The PEL is believed to have a constant charge density and to be evenly distributed throughout the nanopore’s inner wall. This layer has also been referred to as the fixed charge layer for this reason. It is also hypothesized that the permittivity ratios in the solute and PEL areas differ, which leads to ion partitioning phenomena. The Debye–H \(\ddot{u}\) ckel approximation is used to derive the induced potential expressions at the interior and exterior of the PEL from the Poisson–Boltzmann distribution. We take Navier–Stokes equation into account to estimate the axial velocity for the Newtonian fluid. The species concentration distribution is calculated by deducing the convection–diffusion in PEL and electrolyte zones. The goal of this work is to examine the hydrodynamic behaviour of the velocity and concentration distribution for several dimensionless parameters that appear in the mathematical model, such as the scaled Debye–H \(\ddot{u}\) ckel parameter, scaled charge density, softness parameter and oscillating electric field. Due to the angular frequency effect, the oscillating Reynolds number leads to a lack of uniformity in the flow field. With a larger value of the oscillating Reynolds number, the axial velocity and specie concentration distribution oscillate more frequently. When the PEL thickness tends to zero and the flow parameters are in good agreement with the rigid nanopore, the PEL-surrounded nanopore approaches the rigid nanopore. Due to the PEL’s applied resistance force towards the electrolyte ions, the flow amplitude decreases as scaled charge density and softness parameter values increase.