Flow and dispersion in anisotropic porous media: a Lattice-Boltzmann study

TL;DR

This study uses Lattice-Boltzmann simulations to explore how fiber orientation in anisotropic porous media affects flow and dispersion, aiming to optimize diffusion layers in energy storage devices like flow batteries.

Contribution

It provides new insights into how fiber orientation influences drag and dispersion, guiding the micro-structural design of porous media for improved flow battery performance.

Findings

Aligning fibers streamwise reduces drag.

Streamwise fiber orientation maximizes dispersion.

Optimized fiber orientation enhances diffusion in flow batteries.

Abstract

Given their capability of spreading active chemical species and collecting electricity, porous media made of carbon fibers are extensively used as diffusion layers in energy storage systems, such as redox flow batteries. In spite of this, the dispersion dynamics of species inside porous media is still not well understood and often lends itself to different interpretations. Actually, the microscopic design of efficient porous media which can potentially and effectively improve the performances of flow batteries, is a still open challenge. The present study aims to investigate the effect of fibrous media micro-structure on dispersion, in particular the effect of fiber orientation on drag and dispersion dynamics. Several Lattice-Boltzmann simulations of {flows through} differently-oriented fibrous media coupled with Lagrangian simulations of particle tracers have been performed. Results show that orienting fibers preferentially along the streamwise direction minimizes the drag and maximizes the dispersion, which is the most desirable condition for diffusion layers in flow batteries applications.