Numerical Study of Suspension Viscosity Accounting for Particle–Fluid Interactions Under Low-Confinement Conditions in Two-Dimensional Parallel-Plate Flow
2025
Junji Maeda | Tomohiro Fukui
Suspensions are prevalent in daily life and serve various purposes, including applications in food, medicine, and industry. Many of these suspensions display non-Newtonian characteristics stemming from particle&ndash:fluid interactions. Understanding the rheology of suspensions is critical for developing materials for applications across different fields. While Einstein&rsquo:s viscosity formula is recognized as a key evaluation tool for suspension rheology, it does not apply when the solvent is a non-Newtonian fluid. Consequently, we explored how changes in the microstructure of suspensions influence their rheology, specifically focusing on changes in relative viscosity, through numerical simulations. The computational approaches used were the regularized lattice Boltzmann method and the virtual flux method. The computational model used was a two-dimensional parallel-plate channel, and the flow properties of the solvent were represented using the power-law model. Consequently, multiple particles migrated to two symmetrical points relative to the center, achieving mechanical equilibrium and moving closer to the center as the power-law index increased. Furthermore, the relative viscosity observed was lower than that predicted by Einstein&rsquo:s viscosity formula, indicating that shear thinning could occur even with a power-law index above 1. Additionally, as the power-law index decreased, the relative viscosity also decreased.
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