Effective permeability conditions for diffusive transport through impermeable membranes with gaps

Fuente: arXiv
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Main Authors: Brennan, Molly, Yeo, Edwina F., Pearce, Philip, Dalwadi, Mohit P.
Format: Preprint
Published: 2025
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author Brennan, Molly
Yeo, Edwina F.
Pearce, Philip
Dalwadi, Mohit P.
author_facet Brennan, Molly
Yeo, Edwina F.
Pearce, Philip
Dalwadi, Mohit P.
contents Membranes regulate transport in a wide variety of industrial and biological applications. The microscale geometry of the membrane can significantly affect overall transport through the membrane, but the precise nature of this multiscale coupling is not well characterised in general. Motivated by the application of transport across a bacterial membrane, in this paper we use formal multiscale analysis to derive explicit effective coupling conditions for macroscale transport across a two-dimensional impermeable membrane with periodically spaced gaps, and validate these with numerical simulations. We derive analytic expressions for effective macroscale quantities associated with the membrane, such as the permeability, in terms of the microscale geometry. Our results generalise the classic constitutive membrane coupling conditions to a wider range of membrane geometries and time-varying scenarios. Specifically, we demonstrate that if the exterior concentration varies in time, for membranes with long channels, the transport gains a memory property where the coupling conditions depend on the system history. By applying our effective conditions in the context of small molecule transport through gaps in bacterial membranes called porins, we predict that bacterial membrane permeability is primarily dominated by the thickness of the membrane. Furthermore, we predict how alterations to membrane microstructure, for example via changes to porin expression, might affect overall transport, including when external concentrations vary in time. These results will apply to a broad range of physical applications with similar membrane structures, from medical and industrial filtration to carbon capture.
format Preprint
id arxiv_https___arxiv_org_abs_2508_10694
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Effective permeability conditions for diffusive transport through impermeable membranes with gaps
Brennan, Molly
Yeo, Edwina F.
Pearce, Philip
Dalwadi, Mohit P.
Soft Condensed Matter
Analysis of PDEs
Dynamical Systems
Biological Physics
Membranes regulate transport in a wide variety of industrial and biological applications. The microscale geometry of the membrane can significantly affect overall transport through the membrane, but the precise nature of this multiscale coupling is not well characterised in general. Motivated by the application of transport across a bacterial membrane, in this paper we use formal multiscale analysis to derive explicit effective coupling conditions for macroscale transport across a two-dimensional impermeable membrane with periodically spaced gaps, and validate these with numerical simulations. We derive analytic expressions for effective macroscale quantities associated with the membrane, such as the permeability, in terms of the microscale geometry. Our results generalise the classic constitutive membrane coupling conditions to a wider range of membrane geometries and time-varying scenarios. Specifically, we demonstrate that if the exterior concentration varies in time, for membranes with long channels, the transport gains a memory property where the coupling conditions depend on the system history. By applying our effective conditions in the context of small molecule transport through gaps in bacterial membranes called porins, we predict that bacterial membrane permeability is primarily dominated by the thickness of the membrane. Furthermore, we predict how alterations to membrane microstructure, for example via changes to porin expression, might affect overall transport, including when external concentrations vary in time. These results will apply to a broad range of physical applications with similar membrane structures, from medical and industrial filtration to carbon capture.
title Effective permeability conditions for diffusive transport through impermeable membranes with gaps
topic Soft Condensed Matter
Analysis of PDEs
Dynamical Systems
Biological Physics
url https://arxiv.org/abs/2508.10694