Qiuxin Gao

Numerical study of damage ship hydrodynamics

Abstract A RANS based CFD solver with VOF modeling of free surface is employed to investigate the effects of sloshing and flooding on damage ship hydrodynamics. The numerical study includes three research works, i.e. the simulations of forced roll motion of an intact ship, sloshing of water in tank and forced roll motion of a damage ship. The computed roll moments in the tank and at opening were compared. The coefficient of roll damping was obtained and validated against model test data. The results show that the impact of sloshing on damage ship hydrodynamics is frequency dependent. It becomes significant near natural roll frequency of the tank. The phase differences between hydrodynamic and hydrostatic components are increasing with frequency. The flooding at opening of a damage ship tends to alleviate the sloshing impact.

Simulation of Wave Effect on Ship Hydrodynamics by RANSE

The application of advanced numerical methods based on the solution of RANSE and VOF equations on the prediction of ship hydrodynamics is presented. The test cases selected are restrained and free oblique motions of a container ship with the effect of incoming wave. The computed and measured results are compared. The general agreements between calculations and experiments are satisfying.

Study of Froude and Hughes methods by numerical towing tank

The resistance of a cargo ship is calculated by numerical towing tank. RANSE multi-phase parallel solver with K-w SST turbulent model and VOF formulation is applied. Computational results from double model (without free surface) are used to obtain 1+k in Hughes’ method and those with free surface are analyzed by both Froude and Hughes’ approaches to investigate model and full scale correlation. ITTC recommended uncertainty study is carried out to evaluate numerical error due to grid density. The computed wave elevation, wake distribution and resistance components by fine, medium and coarse meshes are cross-compared and validated against experiment data where applicable. It is found that grid resolution has most effect on wave pattern. The predicted friction and viscous-pressure resistance coefficients are relatively grid independent from present numerical simulation