Added Mass and Damping Coefficient Prediction - Results of Different Methods

Added Mass And Damping Coefficient Prediction - Results Of Different Methods Ermina Begovic, University of Naples Federico II, Naples/Italy, begovic@unina.it Guido Boccadamo, University of Naples Federico II, Naples/Italy, boccadam@unina.it Abstract The evaluation of ship motions and loads obtained through seakeeping calculations is continuing to be one of the most important research subject. Numerical procedures used for this purpose are generally validated by ship motions experiment; evaluation of motion equation coefficients is carried out experimentally by forced motions and measurement of exciting forces on restrained model in regular seaway. Even if the motion prediction by some numerical method is satisfactory, the predicted values of particular coefficients from the motion equation (added mass and damping coefficients) and of exciting forces are not always satisfactory. This can affect heavily loads assessment that is fundamental for structure scantlings. In particular, for the widely studied Wigley based hulls (Journee (1992)), big discrepancies between numerical and experimental values have been noted. In this work the review of experimental results for added mass and damping coefficients for heave and pitch available in literature is given. Fo r two Wigley models (Journee (1992)) and for high speed Blok and Beukelmann Model 5 (Keuning (1990)) heave and pitch added mass and damping coefficients are calculated by 2 ½ D high speed theory by Faltinsen and Zhao (1990) with and without cross-flow corrections as proposed by Authors in previous works. Results are compared with numerical results of similar works where different 3D time domain calculation methods were used. Significant differences in some coefficients are found, calling for further investigation on the matter.