Determination of hydrodynamic coefficients of multi-hull ships for seakeeping analysis

Linear and non-linear hydrodynamic coefficients of single and multiple hulls are obtained using the boundary-integral method. For linear frequency-domain analysis, the boundary-integral method based on a simple source distribution (Yeung [50] was used. The nonlinear time domain simulations were carried out using a boundary-integral algorithm based on the mixed Eulerian-Lagrangian (MEL) formulation (Longuet-Higgins and Cokelet [19]). Also, linear time domain simulations were carried out by utilizing a simplified mixed Eulerian-Lagrangian formulation and the steady-state results compared with that obtained from linear-frequency domain analysis. Both 21) and 3D results were obtained for a range of parameters such as beam/draft, hull-separation/beam ratios and frequency and amplitude of hull motions. The results shed light on complex wave-body interactions involved in multi-hull ships and identify critical hydrodynamic and geometric parameters affecting their sea keeping performance. The computational tools developed and the findings thus contribute to design of multi-hull ships for improved at-sea performance.