A framework for efficient irregular wave simulations using Higher Order Spectral method coupled with viscous two phase model

•Higher Order Spectral (HOS) method can efficiently propagate a nonlinear wave field.•Coupling of HOS and CFD as a tool for simulating extreme waves is proposed.•Implemented HOS algorithm is validated.•Coupling of HOS and CFD is validated on irregular wave propagation.•An example CFD simulation of a 3D extreme wave is presented. In this paper a framework for efficient irregular wave simulations using Higher Order Spectral method coupled with fully nonlinear viscous, two-phase Computational Fluid Dynamics (CFD) model is presented. CFD model is based on solution decomposition via Spectral Wave Explicit Navier–Stokes Equation method, allowing efficient coupling with arbitrary potential flow solutions. Higher Order Spectrum is a pseudo-spectral, potential flow method for solving nonlinear free surface boundary conditions up to an arbitrary order of nonlinearity. It is capable of efficient long time nonlinear propagation of arbitrary input wave spectra, which can be used to obtain realistic extreme waves. To facilitate the coupling strategy, Higher Order Spectrum method is implemented in foam-extend alongside the CFD model. Validation of the Higher Order Spectrum method is performed on three test cases including monochromatic and irregular wave fields. Additionally, the coupling between Higher Order Spectrum and CFD is validated on three hour irregular wave propagation. Finally, a simulation of a 3D extreme wave encountering a full scale container ship is shown.