Characterizing shear-thinning fluids transitioning from rheology- to inertia-dominated flow regimes in porous media

• Published in: Journal of hydrology (Amsterdam) 2021-10, Vol.601, p.126498, Article 126498
• Main Authors: Zheng, Lizhi, Wang, Lichun, Wang, Tiejun, Singh, Kuldeep, Zhou, Jia-Qing, Shuai, Pin, Wang, Zhong-Liang, Chen, Xi
• Format: Article
• Language: English
• Subjects: Inertial effects; Non-Newtonian; Nonlinear flow; Pore geometry; Power law fluids; Reynolds number
• ISSN: 0022-1694; 1879-2707
• DOI: 10.1016/j.jhydrol.2021.126498

•CFD simulations of shear-thinning fluids flow through idealized pores were conducted.•The critical Reynolds number was determined when transitioning from rheology- to inertia-dominated flow regimes.•The critical Reynolds number was correlated to fluid rheology and pore geometry. Understanding and predicting non-Newtonian fluid flows in porous media is crucial for many geophysical and environmental problems. Although extensive studies have investigated nonlinear flow for shear thinning fluids, the critical Reynolds number (Rec) for identifying nonlinearity in transition from rheology-dominated to inertia-dominated flows remains unclear. To determine Rec, we conducted hundreds of direct numerical simulations of power law fluids with diverse fluid rheology (quantified by a power law exponent n) through a variety of pore geometries which are characterized by a non-dimensional hydraulic shape factor (β). The numerically-derived pressure gradient and fluid flux were used to compute the bulk viscosity ~ Reynolds number curves, which were further employed to determine Rec. With knowing Rec, we established a predictive function between Rec and (β, n). This function allows for the estimation of Rec based on the measurable properties (β, n) via imaging technique. Our mechanistic modelling work sheds light on predicting nonlinear flow for non-Newtonian fluids at the continuum scale by knowing under what conditions the inertial effects are significant.