Calculations of non-linear waves generated by complex body motion

A structured and unstructured hybrid overlapping grid method is developed f or simulating free-surface waves generated by submerged arbitrary bodies un dergoing rigid body motion in multi-degrees of freedom. Exact boundary cond itions are applied to the transient free and body surfaces. The accuracy, e fficiency and generality of the present two-dimensional code for potential flows are validated by comparisons with available theories and experiments. Numerical experiments are reported in this paper to investigate the non-li near behaviour of waves due to the complex rigid body motion, in terms of w ave patterns and the pressure distribution. Combining the best features of both grid systems for finite elements and finite differences, the present m ethod provides a promising alternative in computational fluid dynamics fbr the design and analysis in marine engineering.