Waves and wrecks: A computational fluid dynamic study in an underwater archaeological site

The modification of waves by shipwrecks and the resulting scour play important roles in shipwreck site formation, and conservation of archaeological sites. The oscillatory flow induced by waves and its interaction with the hull structure at a historic shipwreck site was analyzed using a two phase 2D model based on the Reynolds averaged Navier-Stokes equations and shear stress transport (SST) k-Omega turbulence model, with inputs from field-based bathymetric survey. The relative importance and seasonal variation in hydrodynamic processes were investigated (flow velocity increase, coherent structures and vortex shedding, turbulence and steady current induced by the non linearity of waves). Results demonstrate that frictional velocity and flow increase dominate morphological change in the low wave energy period (LEP), whereas turbulent shear stress and large coherent structures dominate scouring in the high wave energy period (HEP). Furthermore, flow acceleration around the hull structure and recirculation cells originated by wave non-linearities become more prominent in the HEP, modifying the trajectory of the shedding vortex and increasing its capacity to transport sediment. The results demonstrate, for the first time, that computational fluid dynamics is a valuable tool in assessing the wave structure interaction in full scale and realistic morphological conditions at complex shipwreck sites.