High-fidelity simulation of ship and linear shear current interaction

In this paper, the hydrodynamic performance of KCS (KRISO Container Ship) in the presence of a non-uniform shear current is investigated for the first time using high-fidelity CFD (Computational Fluid Dynamics) simulations. Various shear current strength conditions Frs with different directions were considered and results were compared to the ones with no shear current. The studies were conducted for the ship advancing at Fr = 0.26, 0.367. The focus is laid on the shear current effects on the ship resistance as well as the free surface elevation, pressure distribution, vortex structures, boundary layer, and nominal wake. Results showed that the presence of the shear current affects the hydrodynamic performance of the ship profoundly such that it increases/decreases the ship resistance in heading/following shear current with the largest change for the cases with the strongest shear current. The viscous resistance is dominant at Fr = 0.26 for all shear current conditions while the wave resistance is dominant for most cases at Fr = 0.367. The wave resistance reduces as the shear current direction varies from head to following shear current, similar to the theoretical model predictions. The viscous component follows a similar trend. The lateral resistance generated by the cross flow in beam shear current increases with the increase of Frs and the reduce of Fr and it is strongly dominated by the lateral pressure resistance. The Kelvin angle reduces in the head shear current and increases in the following shear current while the beam shear current reduces the Kelvin angle on the windward side of the ship and increases on the leeward side. The shear current also altered the transverse wavelength such that it increased in head shear current and reduced in following shear current. The predicted Kelvin angles and transverse wavelengths confirmed the finding of simplified theories on ship-shear current interaction. The presence of shear current also significantly affects the boundary layer, vortical structures, and the wake field.