CFD Computation of Wave Forces and Motions of DTC Ship in Oblique Waves

摘要

Numerical simulations of the Duisburg Test Case (DTC) ship free to heave, roll, and pitch motions in oblique waves are presented. The computations are carried out by an in-house computational fluid dynamics (CFD) solver, naoe-FOAM-SJTU, based on volume of fluid (VOF) and overset grid methods. An open source library, waves2Foam, is used to generate desired wave conditions and prevent the wave reflecting internally from the computational domain. This study focuses on the short wave; therefore, only one wave length is chosen. The diffraction and radiation effects have significant influence on the nonlinearity of wave forces. The results of longitudinal and lateral mean drift forces reach their maximum values at headings of 60 degrees and 90 degrees, respectively, which is caused by the increment of ship motions and enhancement of wave diffraction. The time history and Fast Fourier transform results of longitudinal and lateral forces show a strong nonlinear property. Then the analysis on ship motions and wave patterns demonstrates that the nonlinearity has a connection with the ship motion and complex wave diffraction and wave slamming. The results of ship motions show that the heave and pitch motions are mainly dominated by wave frequency, whereas the roll motion is correlated with its natural frequency.