Numerical solution and sensitivity analysis of hydrodynamic force derivatives on maneuverability prediction

Aiming at balancing the cost and accuracy of ship maneuvering motion prediction, a numerical calculation based prediction approach is presented, combined with the sensitivity analysis of hydrodynamic derivatives.

First, the numerical calculation is carried out by solving the RANS equations, employing the method of volume-of-fluid (VOF) to capture the free-water surface and putting constraints on the motion of DTMB 5415 model, additional comparison of the linear hydrodynamic derivatives obtained from the regression are conducted with the experimental data so as to verify the validity of the proposed numerical scheme. Furthermore, a ship maneuvering mathematical model of DTMB 5415 is established on the basis of the maneuvering mathematical model group (MMG) method, and the Runge-Kutta algorithm is utilized to solve the equations and the model's turning and zigzag maneuvering motions are simulated. Finally, the sensitivity of the hydrodynamic derivatives of the two maneuvering motions are analyzed.

The results show that the modelling results of ship motion trajectory and parameter for criteria obtained by the proposed methods are agree well with the experimental data, among which the average errors of the parameters of turning and zigzag maneuvering motion are 5.1% and 11.7% respectively. Compared with the results of the self-propelled ship model simulation using CFD, both the accuracy and cost are improved. The sensitivity analysis also verify that some nonlinear hydrodynamic derivatives have little influence on the maneuverability criterion, and can be estimated using empirical formulas.

The proposed method is feasible for ship maneuverability motions prediction, which can meet the engineering application precision and reduce the calculation cost greatly, especially suitable for the maneuverability motions prediction and optimization in ship design stage.