A three-dimensional continuum model is explored to investigate the effects of radially dependent
system parameters, such as relative permittivity and viscosity, on the transport of proton and wa-
ter in nanoscale cylindrical pores of a fully hydrated polymer electrolyte membrane (PEM). The
model employs Poisson, Nernst–Planck, and Stokes equations. Based on evidence from the literature
for the presence of a stagnant water layer near the pore surface, we assume that a no-slip surface
is located inside the pore, a few Angstroms from the pore wall. To solve the system numerically,
the steady-state solution for the transport of protons and water is considered to be a perturbation
around the equilibrium solution. Our results indicate that a radial variation of relative permittivity
has the greatest influence on pore conductivity, reducing it by about 50% when compared to that of
constant permittivity. On the other hand, viscosity plays the dominant role when the effective water
drag within such pores is considered. We conclude that a continuum approach, including constant
viscosity, is applicable in nanoscale models provided that the location of the no-slip surface is prop-
erly specified and the radial variation of the relative permittivity is taken into consideration.
«A three-dimensional continuum model is explored to investigate the effects of radially dependent
system parameters, such as relative permittivity and viscosity, on the transport of proton and wa-
ter in nanoscale cylindrical pores of a fully hydrated polymer electrolyte membrane (PEM). The
model employs Poisson, Nernst–Planck, and Stokes equations. Based on evidence from the literature
for the presence of a stagnant water layer near the pore surface, we assume that a no-slip surface
is...
»