DOI: 10.25909/29850083.v2
title: Revisiting the access conductance of a charged nanopore membrane

description: The files present in both versions of this repository are associated with the following<b> </b>preprint: H. C. M. Baldock and D. M. Huang, “Revisiting the access conductance of a charged nanopore membrane,” (2025), arXiv:2508.07733 [cond-mat.soft]. The files added to make second version of this repository are associated with additional studies that constitute revisions to this preprint.All files are .txt files containing the fluxes calculated inside of the pore (along z=0) from Finite-Element method calculations of electric-field-driven flow in Comsol 4.3a. Columns with "Velocity field, z component (m^3/s)" and "Electric current (A)" indicate the solution flux (in m³/s) and electric current (in A), respectively. The first instance of "Total flux, z component (mol/s)" is the ion flux of the positively charged ion (in mol/s), while its second instance is the ion flux of the negatively charged ion.Columns with "Diffusive electric current (A)", "Convective electric current (A)" and "Electrophoretic electric current (A)" indicate the diffusive electric current, convective electric current and electrophoretic electric current, respectively, at z=0 (all in A). The first instance of "Diffusive flux, z component (mol/s)", "Convective flux, z component (mol/s)" and "Electrophretic flux, z component (mol/s)" is the diffusive ion flux, convective ion flux and electrophoretic ion flux, respectively, of the positively-charged ion at z=0 (all in mol/s); their second instance is that of the negatively-charged ion.Fluxes obtained from simulations of electric-field-driven flow are indicated in the file name by "-dV-". The potential difference (in V) is given in the second column. "a[X]" indicates a fixed pore radius of [X] nm, "c[X]" indicates a fixed bulk electrolyte concentration of [X] mmol/L and "sig[X]" (or "q[X]") indicates a fixed surface charge density of –[X] mC/m² over the parameter sweep. The pore radius and surface charge density is changed over the parameter sweep for files with names containing "-a-" and "-sig-" ("-q[X]-"), respectively, while all other parameters are fixed. The pore radius (in m) or surface charge density (in C/m²) is given in the second column. Note that the file name variable “sig” indicates simulations of electrolyte through a uniformly charged membrane, while “q” is indicative of membranes with surface charge applied only to the pore entrance and interior.All simulations were of electrolyte flow in an ultrathin membrane using the diffusivity constants and ion valences of potassium chloride (KCl) and the viscosity and dielectric constant of water (H<sub>2</sub>O) at an ambient temperature. The length of pore (L) was set to 0.2 nm in all simulations ("L0.2"). All file names contain "-mesh9-res4-P2+P1-c3-V2", which corresponds to the mesh configuration, reservoir size, and discretizations of the Stokes equations, ion concentrations and electric potential as described in the section "Finite-Element Method simulations" in the Supplementary Material of "Revisiting the access conductance of a charged nanopore membrane".This data was generated using the Comsol 4.3a model described in: H.C.M. Baldock, D.M. Huang, <i>Phys. Fluids</i><i> </i>37, 022032 (2025), https://doi.org/10.1063/5.0251773