Uphill transport in competitive drift-diffusion models with volume exclusion

Fuente: arXiv
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Main Authors: Casini, Francesco, Giardinà, Cristian, Nicolini, Jacopo, Selmi, Luca, Vernia, Cecilia
Format: Preprint
Published: 2026
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author Casini, Francesco
Giardinà, Cristian
Nicolini, Jacopo
Selmi, Luca
Vernia, Cecilia
author_facet Casini, Francesco
Giardinà, Cristian
Nicolini, Jacopo
Selmi, Luca
Vernia, Cecilia
contents This paper addresses uphill transport (defined as a regime in which particle flow is opposite to the prescriptions of Fick's diffusion) in drift-diffusion particle transport constrained by volume exclusion. Firstly, we show that the stationary hydrodynamic limit of a multispecies, weakly asymmetric exclusion process (SHDL) naturally predicts precisely characterized uphill regimes in the space of external drivings. Then, with specific reference to systems of oppositely charged particles, we identify well-defined model hypotheses and extensions whereby the SHDL converges to the modified Poisson-Nernst-Planck model, thus bridging the gap between exclusion-based particle models and continuum descriptions commonly used in engineering. The merits and limitations of the models in describing the particle fluxes and predicting uphill transport conditions are investigated in detail with respect to the adopted approximations and simplifications. The results demonstrate the persistence of uphill transport phenomena across modeling scales, clarify the conditions under which they occur, and suggest that uphill transport may play a significant role in nanoscale electrolytes, confined ionic and iontronic devices, and membrane-based technologies.
format Preprint
id arxiv_https___arxiv_org_abs_2602_08583
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Uphill transport in competitive drift-diffusion models with volume exclusion
Casini, Francesco
Giardinà, Cristian
Nicolini, Jacopo
Selmi, Luca
Vernia, Cecilia
Statistical Mechanics
Mathematical Physics
Probability
This paper addresses uphill transport (defined as a regime in which particle flow is opposite to the prescriptions of Fick's diffusion) in drift-diffusion particle transport constrained by volume exclusion. Firstly, we show that the stationary hydrodynamic limit of a multispecies, weakly asymmetric exclusion process (SHDL) naturally predicts precisely characterized uphill regimes in the space of external drivings. Then, with specific reference to systems of oppositely charged particles, we identify well-defined model hypotheses and extensions whereby the SHDL converges to the modified Poisson-Nernst-Planck model, thus bridging the gap between exclusion-based particle models and continuum descriptions commonly used in engineering. The merits and limitations of the models in describing the particle fluxes and predicting uphill transport conditions are investigated in detail with respect to the adopted approximations and simplifications. The results demonstrate the persistence of uphill transport phenomena across modeling scales, clarify the conditions under which they occur, and suggest that uphill transport may play a significant role in nanoscale electrolytes, confined ionic and iontronic devices, and membrane-based technologies.
title Uphill transport in competitive drift-diffusion models with volume exclusion
topic Statistical Mechanics
Mathematical Physics
Probability
url https://arxiv.org/abs/2602.08583