Pore-scale Simulation of Shear-Thinning Fluid Flow using Lattice Boltzmann Method

TL;DR

This study uses lattice Boltzmann simulations to analyze how flow and geometric variables influence the apparent viscosity of shear-thinning non-Newtonian fluids in porous media, revealing key dependencies on porosity and permeability.

Contribution

It introduces a pore-scale simulation approach with stochastic microstructure generation to quantify the scaling factor's dependence on porous media properties.

Findings

Scaling factor strongly depends on porosity and permeability.

Maximum scaling factor occurs near the percolation threshold.

Correlations between scaling factor and macroscopic properties are proposed.

Abstract

Present work attempts to identify the roles of flow- and geometric-variables on the scaling factor which is a necessary parameter for modeling the apparent viscosity of non-Newtonian fluid in porous media. While idealizing the porous media microstructure as arrays of circular and square cylinders, present study uses multi-relaxation time lattice Boltzmann method to conduct pore-scale simulation of shear thinning non-Newtonian fluid flow. Variation in the size and inclusion ratio of the solid cylinders generates wide range of porous media with varying porosity and permeability. Present study also used stochastic reconstruction technique to generate realistic, random porous microstructures. For each case, pore-scale fluid flow simulation enables the calculation of equivalent viscosity based on the computed shear rate within the pores. It is observed that the scaling factor has strong dependence on porosity, permeability, tortuosity and the percolation threshold, while approaching the maximum value at the percolation threshold porosity. Present investigation quantifies and proposes meaningful correlations between the scaling factor and the macroscopic properties of the porous media.