Modelling an energetic tidal strait: investigating implications of common numerical configuration choices

Representation of the marine environment is key for reliable coastal hydrodynamic models. This study investigates implications common depth-averaged model configuration choices in sufficiently characterising seabed geometry and roughness. In particular, applications requiring a high level accuracy and/or exhibiting complex flow conditions may call greater detail representation than typically adopted Ramsey Sound, macrotidal strait Pembrokeshire, Wales, UK considered as case study. The site contains various steeply inclined bathymetric features, including submerged pinnacle named Horse Rock rocky reef called “The Bitches”. available energy Sound’s tidal currents has attracted attention from developers. There interest accurately modelling energetic hydrodynamics surrounding its pronounced bathymetry. solver Thetis applied to simulate Sound. It shown that notable prominent features influence localised and, most importantly, regional characteristics. Bitches” consistently accelerate while induces wake structure reversals. calibrated against bed- vessel-mounted Acoustic Doppler Current Profiler (ADCP) observations, by altering roughness parameterisations. A spatially variable locally scaled Manning coefficient based on diverse classification observations found improve performance comparison uniformly constants, latter more approach. local impact be greatest during spring flood periods velocity currents. Meanwhile, effect coarsening computational mesh around towards values models investigated. Results indicate severe misrepresentation subsequent unless refined element size adequately represents