Ship motion responses and added resistance in waves have been predicted by a wide variety of computational tools including potential and viscous flow methods. However, to validate the computational flow field is still challenging. In the present work, ship vertical motions, added resistance and detailed wake flow field for a 3.2m KRISO container ship (KCS) model in waves have been predicted by simulation and experiment. The force, motions and S-PIV measurement were conducted in towing tank using same ship model. The viscous flow simulation was performed by CFDSHIP-IOWA with rigid body motion solver and dynamic overset grid. The ship heave and pitch motions were considered in wave and in calm water. The current result shows good agreement between simulation and experiment for the trend of the motion responses and added resistance. As wave length increases, heave and pitch motion amplitudes increase from near zero to almost constant one but the added resistance coefficient raises until the peak at λ/L= 1.15. For the nominal wake at propeller plane, the velocity distribution pattern in short waves, e.g. λ/L=0.65, is similar with the calm water one. In long waves such as λ/L=1.15, the bilge vortex moves up and down relative to the stern vertical motions and remains always inside the propeller radius. The secondary vortex is shedding above and below the dummy boss inside the low speed area. The oscillation of nominal wake factor in waves is almost sinusoidal unlike the KVLCC2 one analyzed in our previous study.
The prediction of ship motion and added resistance is very important for economic operation of the ship as well as to assess the seakeeping performances properly. The fuel consumption of a ship is related to the ship motion and added resistance of the ship. The wake profile and the vortex behavior at the propeller plane have definite influence on the propeller performance and hence on the fuel consumption as well. Development of the ship motions and added resistance predictions, by many analytical methods, advanced Potential Flow methods etc., is a long history and is briefly summarized by Wu (2013). With the rapid advancement of computer technology, CFD has recently become more popular tool to analyze seakeeping performances in viscous flow.
