Ship manoeuvring prediction with hydrodynamic derivatives from RANS: Development and application

More and more successful applications of RANS tool to obtain hydrodynamic derivatives or coefficients for ship manoeuvring prediction have been reported in recent years. However, to obtain all required hydrodynamic derivatives from pure RANS simulations will be very time-consuming due to many cases, especially considering dynamic ship motions in water surface and real rotating propeller with dynamic grid approach. This might be one of the limiting factors to apply RANS tool for ship manoeuvring prediction widely, although the relevant numerical methods have been demonstrated to be of acceptable accuracy in many respects. So that, it is quite necessary to explore the appropriate strategies when applying RANS tool for ship manoeuvring prediction, consequently balancing prediction accuracy and time cost as far as possible. In this study, we use the own expanded RANS solver to simulate a series of captive model tests for the oil tanker KVLCC2. Assumptions of double-body flow and body force propeller are introduced during the simulations, in order to reduce computational time. Hydrodynamic derivatives are determined by regression analysis to the computed hydrodynamic forces, and free-running turning test and zig-zag test are simulated by using these derivatives. The RANS method and the whole procedure of manoeuvring prediction are described in this article. The main purpose is to check the applicability of the expanded RANS solver, and to confirm the effectiveness of whole procedure of manoeuvring prediction. It shows that the derivatives from RANS, can be used for manoeuvring prediction, at least for KVLCC2, and the present strategy of ship manoeuvring prediction is quite promising in the respect of the balance of prediction efficiency and accuracy.