Numerical Study of Water Depth Effect on Sway Velocity and Rudder Derivatives of a Container Ship in Manoeuvring

Abstract

Correct prediction of the hydrodynamic derivatives is essential for the accurate determination of ships manoeuvring performance. Numerical and experimental methods are widely used for the determination of these derivatives. Even though experimental methods are more reliable, these facilities are rare and often prohibitively expensive. More viable option, primarily during the early stages of the ship design, is to determine these derivatives numerically. And also most of the ship manoeuvring studies and regulations are on deep water conditions, whereas the ship manoeuvring performance is much worse in shallow waters, and its controllability is difficult. An attempt is made in this paper to study the shallow water effects on the sway velocity-dependent derivatives and rudder derivatives numerically. KRISO container ship (KCS), a benchmark example used by different research groups, is taken for the present study. Straight line or static drift tests are performed in a numerical environment at different drift and different rudder angles using a commercial CFD package. These tests are conducted in both deep and shallow water conditions. Effects of water depth on the sway velocity-dependent hydrodynamic derivatives and rudder derivatives are evaluated, and the results are presented and analysed.