Wave-induced cross-structure loads are presented for a SWATH (Small Waterplane Area Twin Hull) vessel whose hull is made up of simple geometrical shapes. The hydrodynamic problem is solved using the higher-order boundary element method and the generalized modes approach available in the radiation-diffraction program WAMIT (Lee and Newman, 2001). The difference between cross-structure loads computed in earth-fixed coordinates and the same loads computed in body-fixed coordinates is illustrated. In the absence of any damping from viscous effects and separation, the computed free surface elevation in the gap between the hulls exhibits large sloshing at resonant frequencies. The effect of sloshing resonance on the computed loads is shown. A technique proposed by Newman (2004) to simulate the additional damping and thereby obtain more realistic predictions of free surface elevations and cross-structure loads is demonstrated.
Author: Thomas Mathai