The influence of porous media microstructure on filtration

TL;DR

This paper develops a multiscale model to analyze how the microstructure of porous filter media, including random fibers, affects filtration efficiency and media evolution over time.

Contribution

It introduces a generalized multiscale theory for irregular microstructures and an agglomeration algorithm to simulate fiber contact and growth during filtration.

Findings

Microstructure significantly impacts filtration performance.

The model predicts filter lifespan based on fiber growth.

Agglomeration affects permeability and contaminant transport.

Abstract

We investigate how a filter media microstructure influences filtration performance. We derive a theory that generalizes classical multiscale models for regular structures to account for filter media with more realistic microstructures, comprising random microstructures with polydisperse unidirectional fibres. Our multiscale model accounts for the fluid flow and contaminant transport at the microscale (over which the media structure is fully resolved) and allows us to obtain macroscopic properties such as the effective permeability, diffusivity, and fibre surface area. As the fibres grow due to contaminant adsorption this leads to contact of neighbouring fibres. We propose an agglomeration algorithm that describes the resulting behaviour of the fibres upon contact, allowing us to explore the subsequent time evolution of the filter media in a simple and robust way. We perform a comprehensive investigation of the influence of the filter-media microstructure on filter performance in a spectrum of possible filtration scenarios.