Numerical Evaluation of Coarse Particle Transport and Deposition over a Steep Ridge

Coarse-particle deposition over steep terrain is shaped by the mismatch between rapid flow deflection and slower particle motion. We apply an existing Eulerian–Lagrangian numerical model to simulate the transport of 100 µm spherical alumina over a flat floor and a 0.20 m high triangular ridge at an incoming wind speed of 10 m s⁻¹. Wind-tunnel measurements are used to evaluate the simulated flow, particle motion, and surface deposition. For centerline deposition flux, root-mean-square errors normalized by the corresponding mean measured flux are 8.6% over the flat floor and 9.8% over the ridge. Transverse profiles show larger normalized errors of 20.1–40.8%. Over the flat floor, centerline deposition peaks about 3 m downstream of release. With the ridge present, floor deposition is enhanced on the approach and reduced at the sampled lee-side stations, followed by partial downstream recovery. Separate aperture measurements show greater collection at the sampled windward than leeward locations. The approach-region maximum overlaps the flat-floor landing zone; the measured approach-to-lee contrast provides clearer evidence of terrain-associated redistribution. Flow deflection, particle inertia, upstream removal, and wake exchange provide a physical interpretation of this sequence. The model captures the main streamwise redistribution under the tested conditions, although substantial discrepancies remain in some transverse deposition profiles.