Ventilation Twin CFD Meshing Guidelines (Underground)

These guidelines address the unique challenges of underground mine ventilation modeling, where irregular, narrow, and highly branched geometries—often derived from laser scans or CAD/BIM models—demand specialized meshing strategies. Unlike surface or HVAC applications, underground ventilation requires resolving turbulent flow in confined, anisotropic domains with strong directional bias (e.g., along airways), abrupt cross-sectional changes, and localized flow disturbances caused by regulators, fans, and obstructions. The guidelines prescribe hierarchical meshing approaches: coarse global meshes for domain coverage, refined local meshes near critical components (e.g., fan inlets, junctions, and exhaust points), and boundary-layer-resolving prism layers near walls to capture near-wall turbulence (via y⁺-targeted inflation). Mesh independence studies, aspect ratio limits (<100), skewness thresholds (<0.95), and orthogonality checks (>15°) are mandated to ensure solver stability and convergence across transient and steady-state CFD solvers (e.g., ANSYS Fluent, OpenFOAM, or CONVERGE). Furthermore, the guidelines integrate with Mine Digital Twin infrastructure by specifying metadata schemas (e.g., mesh version, coordinate system, source geometry provenance) and interoperable formats (e.g., CGNS, STL with defined normals, or native solver meshes with boundary condition tagging) to enable automated mesh regeneration during twin updates.