Flow structure around a vertical cylinder placed in an open channel under combined wave-current flows

Surface mounted cylinders in combined wave-current flow generate a wide range of coherent structures that include vortex tubes (VT), wake billow vortices (VW), and horseshoe vortices observed in steady flow. Additionally, horizontal near-bed vortices are sometimes generated on the wake side of the cylinder. The formation of these vortices and the forces acting on the cylinder are a function of the ratio between the steady current velocity and the oscillatory velocity (0\ensuremath{\le}U${}_{s}$/U${}_{m}$\ensuremath{\le}1.4) and of the Keulegan-Carpenter number, K${}_{C}$=U${}_{m}$T/D (1.5\ensuremath{\le}K${}_{C}$\ensuremath{\le}30.8), where T is the period of the oscillatory flow.