Abstract

Non-Newtonian fluid flows in porous media are critical in various subsurface and geotechnical engineering applications. However, accurately predicting such flows remains challenging due to complex fluid rheology and intricate pore structures. This study focuses on polymer fluids with shear-thinning rheology. To address the limitations of existing models, we derive a theoretical conductance model for polymer flow in a capillary tube, based on which a customized pore-network method is developed. Simulations reveals three distinct flow regimes, highlighting the impact of complex rheology on flow dynamics. Notably, flow heterogeneity amplifies as the shear-thinning feature directs more flows through wider pores, where the effective viscosity decreases more significantly compared to narrower ones. The conductance model also enables formulating a generalized Darcy's law for non-Newtonian fluids, validated through Pore-network modeling. The proposed framework is adaptable to a broad range of non-Newtonian fluids, offering valuable insights for scaling up to field-scale applications.