Analysis of the Manoeuvring Prediction of a Submarine by CFD Effects of Stern Appendage Configuration

The prediction of the manoeuvring behaviour of a submarine vehicle is usually achieved by means of simplified manoeuvring mathematical models. Broadly accepted mathematical models describing a submarine manoeuvring performance are based on the traditional approach of Gertler and Hagen [1], later on modified by Feldman [2] in order to account for the typical phenomenon characterising the submarine dynamic response, namely the cross coupling effect between yaw and heave-pitch motions. These tools are extremely efficient and fast from the computational point of view because the forcing terms of the Euler rigid body equations, or alternatively, forces and moments acting on the body, are prescribed by means of hydrodynamic derivatives; in other words, hydrodynamic derivatives synthetize hydrodynamic loads acting on a body during a general motion. The success of these tools is strictly dependent on the reliability of the procedure followed for the evaluation of hydrodynamic coefficients. In case of a submarine, derivatives are evaluated ad-hoc case by case, due to critical operational task required for these vehicles.