The influence of a circular moonpool on towing resistance of a conical platform

Abstract

The towing resistance of naval constructions and fuel consumption would increase due to a complicated mechanism known as water motion in a moonpool during transit. To investigate the effects of a circular moonpool on the towing resistance of a conical platform and the characteristics of the flow in the moonpool during the towing operation, both the model test and the numerical simulation approaches were used. Both experimental results and numerical simulations agree well on the total towing resistance. The two's differences are within 10% of one another in terms of absolute value, which shows that the two approaches had good agreement and consistency. The results demonstrate that two vortices have developed in the moonpool. The formation and dissipation of vortices, as well as the resulting change of the water's surface, will result in the loss of energy, increasing the platform's towing resistance. Due to the moonpool, the flow field changes around the platform and raises the differential pressure resistance. In the end, the moonpool will cause a 7%–10% increase in overall towing resistance. The majority of the resistance on the two platforms comes from differential pressure, with frictional resistance making up a very small portion of the total resistance.