CFD verification and validation of added resistance and motions of KVLCC2 with fixed and free surge in short and long head waves

Abstract

The motions and added resistance of KVLCC2 at Fr=0.142 and 0.25 with free and fixed surge in short and long head waves are predicted using URANS and validated against EFD datafor Fr=0.142. Verification studies show the results are fairly insensitive to the grid size and time step. CFD indicates no significant difference between free and fixed surge while EFD pitch motion and added resistance are affected. Added resistance was largest when the bow relative motion has largest amplitude and is about 180° out of phase with the waves. The decomposition of forces and moments works well for first harmonics but not for higher harmonics originated from radiation in long waves and diffraction in very short waves. Maximum responses occur near the resonance condition and near the maximum wave excitation force which is at λ/L=1.33 and long waves for surge/pitch and heave, respectively. Potential flow predictions for motions and the added resistance are further from the data than CFD. Local flow analyses show that added resistance is mainly induced by high pressure on the upper bow which is correlated with bow relative motion. The unsteady wave pattern is analyzed and the wake flow is compared with PIV measurements. © 2012 Elsevier Ltd.