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Finite volumes for a generalized Poisson-Nernst-Planck system with cross-diffusion and size exclusion

Abstract

We present two finite volume approaches for modeling the diffusion of charged particles, specifically ions, in constrained geometries using a degenerate Poisson-Nernst-Planck system with cross-diffusion and volume filling. Both methods utilize a two-point flux approximation and are part of the exponentially fitted scheme framework. The only difference between the two is the selection of a Stolarsky mean for the drift term originating from a self-consistent electric potential. The first version of the scheme, referred to as (SQRA), uses a geometric mean and is an extension of the squareroot approximation scheme. The second scheme, (SG), utilizes an inverse logarithmic mean to create a generalized version of the Scharfetter-Gummel scheme. Both approaches ensure the decay of some discrete free energy. Classical numerical analysis results-existence of discrete solution, convergence of the scheme as the grid size and the time step go to 0-follow. Numerical simulations show that both schemes are effective for moderately small Debye lengths, with the (SG) scheme demonstrating greater robustness in the small Debye length regime.
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Dates and versions

hal-04022357 , version 1 (09-03-2023)

Identifiers

  • HAL Id : hal-04022357 , version 1

Cite

Clément Cancès, Maxime Herda, Annamaria Massimini. Finite volumes for a generalized Poisson-Nernst-Planck system with cross-diffusion and size exclusion. 2023. ⟨hal-04022357⟩
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