Fully Nonlinear Wave-Body Interactions with Fully Submerged Dual Cylinders

A 2D fully nonlinear NWT is developed based on the potential theory, mixed Eulerian-Lagrangian (MEL) time marching scheme, and boundary element method (BEM). Wave deformation and wave forces on submerged single and dual cylinders are calculated using the NWT. The computed mean, 1 st , 2 nd , and 3 rd order wave forces on a single submerged cylinder are compared with those of Chaplin's experiment, Ogilvie's 2 nd -order theory, and another nonlinear computation called high-order spectral method. The computed mean, 2 nd and 3 rd harmonic forces agree well with lab measurement but there exists noticeable discrepancy in the 1 st -order wave forces as KC number increases, which can be contributed to viscous effects (clock-wise circulation around the body). An independently developed 2D viscous NWT confirmed this speculation. The NWT simulations for submerged dual cylinders show that the interaction effects can be significant when the gap is small. In particular, the higher-harmonic forces on the rear cylinder can be greatly increased due to already-deformed incident waves by the front cylinder. The potential NWT results for dual cylinders are also compared with those including viscous effects.

Fully Nonlinear Wave-Body Interactions with Fully Submerged Dual Cylinders Conference Paper