Elimination of over-predicted heave and pitch motions of catamarans at resonance frequency

For the special ship like catamaran, which has a unique structure with gap resonance, the traditional potential method tends to over-predict the motion at the resonance frequency due to the negligence of fluid viscosity. In this paper, a new method considering damping is put forward to inhibit over-predicted heave and pitch response. Viscous damping is introduced into free surface boundary conditions. Critical damping is added in the motion equations. Numerical simulations of a HEU catamaran and a DUT catamaran are performed. It is found both viscous damping and critical damping can weaken the over-predicted resonant responses. However, the method of adding critical damping is much more efficient at high speeds and the results conform better to the experimental results.