Three-dimensional finite-volume modelling and laboratory validation of non-Darcy flow in rough rock fractures

This study presents a systematic investigation into non-Darcy fluid flow through rough-walled rock fractures to elucidate the complex interplay between fracture geometry, surface roughness, and hydraulic conditions. The research integrates high-resolution 3D finite-volume numerical simulations, solving the full Navier-Stokes equations, with rigorous experimental validation. Laboratory tests were performed on 3D-printed fracture models with precisely controlled roughness (Joint Roughness Coefficient, JRC), confirming the numerical model’s accuracy with flow rate deviations under 3%. The validated model was then used for a comprehensive parametric analysis. Key findings reveal that surface roughness is a dominant parameter, reducing fracture permeability by up to 60% and inducing complex flow channelization. Crucially, non-Darcy flow behavior emerges at Reynolds numbers as low as 0.86, challenging …