A Rankine source computation for three dimensional wave–body interactions adopting a nonlinear body boundary condition

• A Rankine source scheme is combined with Euler–Lagrange method.
• Wave–body interactions with exact nonlinear boundary condition are examined.
• A new free surface source distribution is developed.
• The numerical scheme for the source distribution is computationally efficient.

A three-dimensional wave–body interaction problem is numerically simulated by a Rankine source scheme in combination with a mixed Euler–Lagrange method. Singular free surface source points are placed exterior to the free surface, which is known as a desingularized method, and free surface boundary conditions are satisfied along control points on the computational domain. A new source distribution algorithm incorporating vertical desingularized distance and horizontal free surface source arrangements is developed and the method connects body panel size to free surface panel size. The nonlinear or exact body boundary condition is captured by regridding the wetted body surface at each time step. A Lagrangian frame of reference is used to capture the motion of singularities during the regridding process. The nonlinear effects caused by the variation of the wetted body surface are evaluated based on this method. The numerical scheme of study is shown to be computationally efficient and computation time is significantly reduced in comparison with earlier numerical investigations using the desingularized method.