A predictive model for porous media tortuosity and specific surface area based on the temporal phase difference of mineral dissolution morphology

Tortuosity and specific surface area (SSA) are critical parameters for characterizing the pore structure of porous media, with broad applications in subsurface flow, geotechnical engineering, and materials science. However, direct measurement of tortuosity and SSA is often challenging and time-consuming. Therefore, developing predictive models for these parameters offers significant scientific convenience and computational efficiency. In geological systems, mineral dissolution under varying hydrodynamic conditions is typically heterogeneous. At present, there is a lack of predictive models that consider tortuosity and SSA in the context of heterogeneous mineral dissolution under different hydrodynamic regimes. This study introduces the concept of the temporal phase difference of mineral dissolution morphology and, based on this, establishes predictive models relating tortuosity and SSA to porosity. Using pore-scale numerical simulations grounded in phase-field theory, the morphological differences in pore structure evolution are analyzed. These results validate the scientific soundness of the proposed temporal phase difference concept and confirm the effectiveness of the developed models in predicting pore structure evolution under heterogeneous mineral dissolution conditions driven by distinct hydrodynamic environments. The proposed model significantly improves the predictive accuracy of the widely used Kozeny–Carman model for permeability. This research provides methodological and modeling support for the determination of tortuosity and SSA in porous media, contributing to advancements in subsurface flow and related disciplines.