Effective Diffusion in Fibrous Porous Media: A Comparison Study between Lattice Boltzmann and Pore Network Modeling...

Area of Science:

• Materials Science
• Computational Physics
• Chemical Engineering

Background:

• Understanding the relationship between pore structure and diffusion is vital for optimizing porous fibrous materials in energy applications.
• Lattice Boltzmann Method (LBM) and Pore Network Modeling (PNM) are key techniques for pore-scale simulation, but direct comparisons are scarce.

Purpose of the Study:

• To compare the effectiveness of LBM and PNM in predicting diffusion transport properties of fibrous porous materials.
• To validate PNM against LBM for virtual material design and performance optimization.

Main Methods:

• Reconstructed stochastic fibrous structures using X-ray microtomography data.
• Performed diffusion simulations using D3Q7 LBM and watershed-derived PNM.
• Estimated pore network parameters, specifically throat radius, using cross-section area equivalent radius.

Main Results:

• Effective diffusion coefficients from LBM and PNM showed good agreement.
• In-plane diffusivity was slightly higher than through-plane diffusivity, consistent with laid fiber structures.
• Tortuosity values derived from both geometric and transport measurements aligned with diffusion coefficient anisotropy.

Conclusions:

• PNM, when using cross-section area equivalent radius for throat size, provides reliable diffusion predictions comparable to LBM for fibrous porous materials.
• The findings support the use of PNM for efficient virtual design and optimization of these materials.
• The study highlights the anisotropy of diffusion in laid fibrous structures and validates tortuosity as a relevant metric.