ncts

Fluid-ion transport through a nanochannel can be described through fourth order-Poisson-Nernst-Planck-Bikerman model coupled with the Navier-Stokes (4PNPBik-NS) equations [1,2]. Fourth order-Poisson-Nernst-Planck-Bikerman (4PNPBik) equations model ionic and nonionic interactions between particles and includes the effect of polarization of the medium, electrostatic correlations, solvation of ions, finite size of particles etc. Navier-Stokes equations model the hydrodynamics of the system. Viscoelectric and electroviscous effects and velocity slip have been considered to better approximate the hydrodynamics at nanoscale. Viscoelectric effect represents the modification of viscosity of the fluid due to interaction between water molecules and electric double layer. Electroviscous effects can be expressed as external electrostatic force acting on the fluid. Additionally, inhomogeneous coefficient of diffusion is considered. Governing equations are discretized using lattice Boltzmann method (LBM). Electroviscous and viscoelectric effect are shown to reduce the flow velocity whereas the velocity slip enhances the flow. Inclusion of steric effect and variable diffusion coefficient resulted in the reduction of electroviscous effect thus causing smaller reduction in fluid velocity. Additionally, impact of steric effect on flow also depended significantly on external concentration of ion species.