OpenFOAM finite volume method implementation of a fully nonlinear potential flow model for simulating wave-structure interactions

We develop an interface-tracking algorithm to solve the twodimensional time dependent free surface flows using a finite volume method with full nonlinear free surface boundary conditions and moving grids. The velocity potential is obtained inside the fluid domain by solving a mixed boundary value problem. The velocity is then calculated by the gradient of the velocity potential. The motion of the free surface is captured by integrating in time the kinematic boundary condition, which is based on the free surface volume flux. In the implemented scheme, the free surface is allowed to deform and a new mesh is generated at each time step. The basis of this model is the freely available open-source computational fluid dynamic toolbox OpenFOAM®. We examine the spatial and temporal convergence of the scheme. We also compare wave periods and evolution of wave amplitudes for a range of wave conditions with the analytical solutions, and a good agreement is found. The solver is intended to be a first step towards an advanced numerical wave tank solving both incompressible and compressible flows interacting with structures undergoing large body motions.