A meshless scheme on the electrokinetically driven flow of power-law fluid through nanochannel considering dual effects of heterogeneity in wall charge and surface wettability

Abstract

The present article deals with the development of a meshless scheme to study the electrokinetically driven flow of non-Newtonian fluid through narrow confinement. Combined impact of patterned charge and hydrodynamic slip length along the channel walls is considered. The widely employed power-law model is adopted to consider non-Newtonian behaviour of the background electrolytic medium. The mathematical model to study the transport of ionized liquid consists of the Poisson equation for electrostatic potential, Nernst–Planck equations for conservation of mass of mobile electrolyte ions and the Cauchy momentum equations along with equations of continuity for the flow field. We further delineated the impact of complex flow physics on the mixing efficiency of the uncharged solute injected from the inlet. The present study has two different aspects, on one hand, the successful implementation of meshless scheme based on radial basis functions and on the other hand, to dictate the impact of patterned charge and hydrodynamic slip length on the overall electrokinetic transport of ionized liquid and its effect on the mixing of injected uncharged solute. Going beyond the widely employed Debye-Hückel approximation, we simulate the governing equations using meshless scheme based on Radial Basis Functions (RBF). The numerical results are found to be in close agreement with the available theoretical and experimental results. The computational results are further presented to indicate the impact of pertinent parameters on the flow modulation and mixing of uncharged solutes. • Combined impact of patterned charge and hydrodynamic slip length of channel walls on the electrokinetic flow modulation is considered. • Power-law model is adopted to consider the non-Newtonian rheology of the fluidic medium. • Radial basis function based meshless scheme is employed for the numerical simulation. • Impact of variable surface charge and slip length on flow modulation is analysed for maximum throughput. • Impact of modulated flow field on the mixing efficiency of injected uncharged solutes is further illustrated.