Full-scale URANS prediction of a vessel's transverse stability in wind and waves under lifting condition

Abstract

Predicting a vessel’s motion response is important for the design as well as evaluating its operability and sustainability. This is often performed in towing tanks through captive model tests in towing tanks. However, discrepancies exist between model-scale and full-scale results. Besides, quite often, the wind is not included in the test, resulting in unrealistic assumptions of static pressure and constant heeling lever from the wind. This paper presents a study on transverse stability under wind, waves, and lifting conditions, incorporating several series of URANS-based simulations in model-scale and full-scale. According to the results, scaling effects accounts for about 3~15% in terms of roll amplitudes and it seems to be both frictional-force-related and wave-frequency-dependent. Wind force exerts limited influence on the vessel’s transverse stability, however, in waves especially for longer wavelength, a wind of 25 m/s increases the roll amplitude up to 53% and it appears to be wave frequency-dependant. The correlation between roll motion and wind/waves/lifting is complicated but their combination produces way more influence than any individual factor alone, indicating none of them should be neglected.