JOURNAL OF ROCK MECHANICS

JOURNAL OF ROCK MECHANICS

Validation of numerical simulation of fluid flow through rough rock fractures using physical modeling based on 3D printing

Document Type : Original Article

Authors
Ahmad Rahmani Shahraki
Alireza Baghbanan
Amin Azhari
Ali Askarpour Kabir
Amirhossein Vahedi
Sina Mirzabeigi
Department of Mining Engineering, Isfahan University of Technology, Isfahan, Iran
10.22034/irsrm.2025.530650.1063
Abstract
Accurate prediction of fluid transport through fractured rocks is critical for groundwater management, hydrocarbon recovery, geothermal energy extraction, and subsurface waste isolation. Classical cubic‑law formulations fail when aperture variability and surface asperities dominate flow resistance, necessitating full Navier–Stokes modelling. Such models, however, require high‑quality experimental data for calibration and validation. Conventional casting or engraving cannot reproduce field‑scale roughness repeatably. This research addresses these challenges by combining precise additive manufacturing of fracture geometries with a pressure‑controlled permeameter, delivering reproducible datasets for numerical verification and future parametric studies. Surface topographies representing JRC 0, 10 and 20 were generated in CAD, respecting a 54 mm diameter and 110 mm length to fit a Hoek triaxial cell. The halves were printed from rigid photopolymer, sealed, water‑saturated, and assembled. A perforated 3D‑printed distributor ensured uniform inflow. Upstream head levels produced inlet pressures of 195, 293, 391 and 489 Pa; lateral confinement of 1–2 bar prevented side leakage. Outflow was weighed at one‑minute intervals until steady conditions were reached. Numerical meshes employed hexahedral elements refined near asperities. Incompressible, laminar Navier–Stokes equations were solved with a coupled pressure–velocity algorithm; convergence was accepted at residuals <10⁻⁶. Discharge increased linearly with inlet pressure for every roughness, yet absolute flow rates decreased as JRC rose. At 195 Pa, measured flow declined from 538 mL min⁻¹ (JRC 0) to 431 mL min⁻¹ (JRC 20); simulations predicted 524 mL min⁻¹ and 419 mL min⁻¹ respectively. Maximum deviation across all cases was 4.8 %, attributable to minor printing tolerances and sensor resolution. The validated CFD model accurately captures roughness‑controlled head losses and is extensible to intersecting fractures, non‑Darcy regimes, and thermo‑hydraulic coupling. Practically, the combined laboratory–numerical platform offers a dependable means for parameterizing permeability in fractured reservoirs and for benchmarking up‑scaled network models.
Keywords
Rough fracture
3D printing
Numerical fluid flow simulation
Experimental permeability
Navier-Stokes equations
Subjects
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JOURNAL OF ROCK MECHANICS
Volume 8, Issue 4
Winter 2025
Pages 53-64