Numerical simulation of free-running turning test of ship in waves

In this study, the turning abilities of a KVLCC2 vessel in calm water and waves are studied using free-running simulations based on an open-source computational fluid dynamics (CFD) library. The flow fields are governed by the unsteady Reynolds-Averaged Navier-Stokes (RANS) equations with the stabilized k-omega SST turbulence modeling. To imitate free-running ships, the overset method is employed with body force propeller modeling. The numerical method is verified by conducting an uncertainty analysis suggested by the ITTC for the calm-water turning. In addition, it is validated for the various wave conditions selected in this study. Then the effects of wavelength and wave direction are studied. The results show difference within 15% with experimental data of turning parameters, trajectories, and time signals of the ship responses. During the turning phase, separate flows due to the ship drift angle caused a notable reduction in pressure near the propeller hub. The effect of the wavelength on the ship turning ability is the most remarkable for short wavelengths, mainly due to the increased sway wave drift force, causing a loss in the ship drift angle. The wave direction had a significant influence on the initial turning characteristics; however, as time passed, the turning characteristics remained unchanged.

Automated summary

This study investigates the turning abilities of a KVLCC2 vessel in calm water and waves using free-running simulations based on an open-source computational fluid dynamics (CFD) library. The results show that the wavelength and wave direction have significant effects on the turning ability, but the turning characteristics remain unchanged over time.