선체부과물 효과를 고려한 자유횡동요 감쇠운동의 CFD를 이용한 모사

Abstract

The roll motion is one of the most important responses of a ship in waves. Potential flow based theories, although they reproduce the heave and pitch motions very well, are much less effective in predicting the roll motion due to the negligence of fluid viscosity. This shortfall is usually compensated by introducing a viscous roll damping component. However, it is not even simple because of nonlinear characteristics due to the effect of fluid viscosity and strong dependence on the forward speed of a ship. Moreover, the appendages such as bilge keels and rudders make the problem much complicated. The present study shows Unsteady RANS based approach to simulate the free roll decay motion for a ship. The WAVIS (Ver. 2.0) code is extended to simulate roll decay motion, which is originally developed for the predictions of resistance and propulsion performance of a ship in MOERI. The numerical simulation is applied to the DTMB 5512 model ship, which has the experimental results obtained in INSEAN (Italian Ship Model Basin) towing tank. Roll decay motions are simulated both at the Froude number zero and 0.138 with and without bilge keels. The results show that CFD-based approach is very promising to predict the roll damping force.