Abstract
A modular-based mathematical model is adopted to predict the maneuvering performance of surface ships in calm water. The model coefficients are determined from a series of captive model simulations performed with computational fluid dynamics (CFD). The maneuvering characteristics obtained from captive CFD simulations are compared to an empirical-based prediction. Two approaches to predicting the propeller actions are investigated: a body force model and a discretized propeller model. The accuracy of the mathematical model is evaluated for turning circle and zig-zag maneuvers by comparison against free running model test data and CFD simulations. Good agreement between predicted maneuvering characteristics and model test data is obtained using model coefficients developed from captive CFD simulations with a discretized propeller model; 3 ? 5% averaged relative error in trajectory parameters for 25o and 35o turning circle and 20-20 zig-zag maneuvers. The averaged relative errors of predicted trajectory parameters for the three maneuvers developed from CFD employing the body force propeller model are around 10 ? 12%. The accuracy of maneuvering prediction is deteriorated significantly with the empirical hull coefficients. Sensitivity of the mathematical model to a set of propeller-rudder interaction parameters is demonstrated by 5 ? 7% deviations about the mean in turning circle characteristics. Sensitivity of the zig-zag maneuver to the interaction parameters is less pronounced. Influence of the propeller side force on the maneuvering performance is examined and a reduction in the predicted steady turn diameter exceeding 20% is found in its absence.
