Accurate modeling of nonlinear flow in porous-fractured media is crucial for revealing complex mechanisms, predicting fluid flow behavior, and identifying potential failure modes, such as anomalous flow channeling or formation damage. Traditional models often struggle to capture the complex interactions between fractures and the surrounding porous media, especially under nonlinear flow conditions. This study presents a multi-scale modeling approach to simulate nonlinear flow behavior in porous-fractured media using the bond-based peridynamic theory. The approach divides the model into three components: the porous matrix, fractures, and fluid exchange between them, allowing for a detailed representation of fluid flow performance. The study focuses on nonlinear flow in porous and fractured media, considering factors such as nonlinear index, fracture aperture, nonlinear fluid exchange properties, and microfractures. Two examples are used to validate the effectiveness and accuracy of the proposed modeling approach: two-dimensional flow in porous-fractured rock masses and nonlinear flow in a porous sand column. The results demonstrate that the proposed multi-scale nonlinear flow model effectively captures complex flow behavior in porous-fractured media, including the influence of nonlinearity and microfractures on fluid flow behavior and the distinct characteristics of pore pressure evolution. Moreover, the model can accurately simulate nonlinear fluid exchange between fractures and the surrounding matrix. This study also explores the significant effects of nonlinear indices and fracture characteristics on flow behavior, providing valuable insights into assessing hydraulic conductivity and predicting flow behavior in porous-fractured media.
Zhang et al. (Thu,) studied this question.