Hydrodynamics on circular cylinder close to a wall: Effects from wall boundary layers

We present a study on the hydrodynamics of a circular cylinder close to a wall, which is an idealized representative of subsea pipelines and cables used in both offshore oil and gas and marine renewable energy industries. This research utilizes Computational Fluid Dynamics (CFD) modeling method to investigate the influences of the boundary layer turbulence and the cylinder-to-floor distance on hydrodynamic forces. A significant jump in hydrodynamic forces is observed over the range of Reynolds number that coincides with boundary layer transition from laminar to turbulence. This transition gives rise to a drop in the size of the thickness of the boundary layer at the location of the cylinder. The force jump is also characterised by a pressure increase on the upwind surface of the cylinder, while the pressure decreases on the leeward surface.