Session: 11-17-01: Micro/Nanofluidics 2025 - Fluid Engineering in Micro- and Nanosystems

Paper Number: 165299

Impact of Porosity and Particle Size on Diffusion in Porous Media: A 2D Lattice Boltzmann Approach 

The study of fluid transport in porous media is key for numerous applications in science and engineering. Several applications and devices, such as fuel cells, filtration processes, geological storage, and transport in porous media, are currently being studied. From a modeling point of view, knowing how diffusion parameters behave when microstructural variations are considered is a step forward to accomplishing a more detailed and precise model prediction. As widely known, hydraulic tortuosity is commonly approximated as a function that only depends on the bulk porosity without considering other variables such as particle size or the shape of the solid particles. This work analyzes the impact of the porosity and particle size on fundamental parameters like hydraulic tortuosity, normalized diffusion coefficient, and permeability. Two-dimensional digitally created porous media have been considered to evaluate the mentioned parameters, and the Lattice Boltzmann method (LBM) has been implemented to compute the velocity field within the pore material. In-house code has been developed, and the input variables are the bulk porosity of the media and the particle size.

Pore domains are created considering the solid particles impermeable and randomly distributed within the domain. The LBM allows the recovery of the fluid behavior through the pores, considering the morphological information. Hydraulic tortuosity is computed taking into account the velocity field in the pore space and the main flow direction. The normalized diffusion coefficient is determined based on the previous parameters, bulk porosity, and hydraulic tortuosity. Given the flow conditions, i.e., creepy flow conditions, Darcy´s law is used to compute the permeability of the generated porous media. In addition, the local porosity for the porous media is determined and presented as results. This is possible since a gradient pressure is applied to the inlet and outlet side of the domain.

For each bulk porosity, fifty samples were evaluated, considering ten samples for every particle size. In the end, one hundred and fifty samples were included in the current study. The obtained results showed significative trends related to the morphological microstructure of the porous media. In particular, it was observed that the tortuosity and permeability are affected by the particle size and porosity, as expected. The study's novelty relies on the proposed correlations between the different variables, which will help predict the diffusion parameters more precisely. Results are compared with previous theoretical and empirical models, showing the advantages and limitations of the LBM approximation. This study contributes to developing more precise models for analyzing porous media and their applications.

Presenting Author: Mayken Espinoza Andaluz ESPOL

Presenting Author Biography: Mayken Espinoza-Andaluz is a full Professor at the Faculty of Mechanical Engineering and Science Production (FIMCP) at ESPOL University (Ecuador). He received his PhD from the Department of Energy Sciences at Lund University (Sweden). He also holds a Licentiate Degree in Heat Transfer, a title commonly used in the Nordic countries as a mid-step between the M.Sc. and the PhD degree. In addition, he obtained a Renewable and Hydrogen Technology Certificate from Hochschule Stralsund (Germany). Pedagogically, he is a Master in Physics Teaching, a title acquired before his PhD.

Mayken is fully dedicated to the generation of knowledge and scientific divulgation. His scientific contributions are related to green energy systems/devices from the micro- and mesoscale to the system scale. Modeling, experimentation, and characterization are the backbones of Mayken´s research group. According to the Scopus Database, scientific production is 66 publications (22 are published in journals Q1 during the last five years). He is also the official voice from ESPOL on the topic “Hydrogen and Fuel Cells”. H-index:16 according to Scopus. Google Scholar - H-index:17, i-index:30.

Authors:

Mayken Espinoza Andaluz ESPOL
Brayan Ordoñez-Saca ESPOL
Jordy Santana-Villamar ESPOL
Carlos Vallejo-Cervantes ESPOL
Martin Andersson Lund University