Mathematics Faculty Articles

Title

A conservative finite difference scheme for Poisson–Nernst–Planck equations

Document Type

Article

Publication Date

2014

Publication Title

Journal of Computational Electronics

Keywords

Electrodiffusion, Finite difference, Ion channel modeling, Poisson–Nernst–Planck equations

ISSN

1569-8025

Volume

13

First Page

235

Last Page

249

Abstract

A macroscopic model to describe the dynamics of ion transport in ion channels is the Poisson–Nernst–Planck (PNP) equations. In this paper, we develop a finite-difference method for solving PNP equations, second-order accurate in both space and time. We use the physical parameters specifically suited toward the modeling of ion channels. We present a simple iterative scheme to solve the system of nonlinear equations resulting from discretizing the equations implicitly in time, which is demonstrated to converge in a few iterations. We place emphasis on ensuring numerical methods to have the same physical properties that the PNP equations themselves also possess, namely conservation of total ions, correct rates of energy dissipation, and positivity of the ion concentrations. We describe in detail an approach to derive a finite-difference method that preserves the total concentration of ions exactly in time. In addition, we find a set of sufficient conditions on the step sizes of the numerical method that assure positivity of the ion concentrations. Further, we illustrate that, using realistic values of the physical parameters, the conservation property is critical in obtaining correct numerical solutions over long time scales.

Comments

X. Li is partially supported by the NSF grant DMS-0914923 and C. Liu is partially supported by the NSF grants DMS-1109107, DMS-1216938 and DMS-1159937.

Additional Comments

Copyright © 2013, Springer Science Business Media New York

ORCID ID

0000-0001-7817-4308

DOI

10.1007/s10825-013-0506-3

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