Computational fluid dynamics simulations of gravity wave flows

Abstract

OpenFOAM and FEniCS are two solver frameworks for solving computational fluid dynamics problems. The former employs the finite volume method to discretize the governing equations, while the latter employs the finite element method. In this thesis we compare models using these two frameworks for three different wave problems. These are internal solitary waves, solitary surface waves, and the generation of waves due to an object oscillating in heave. Before running each specific case, the solver models are validated using benchmark cases or intuitive test cases, to make sure that we can rely on the numerical results to a fairly high degree. The internal wave case simulations are based on and are compared to published results. We find a good agreement in our results to the published results. For the solitary wave case, we analyze conservation of mass and energy for a solitary propagating wave with analytically constant shape and velocity. Energy and mass is found to be conserved better in OpenFOAM than in FEniCS, but with a converging improvement in FEniCS with mesh refinement. In the final case chapter, the added mass and damping coefficients for an object oscillating in heave are computed and compared with analytical results. The FEniCS simulations do unfortunately crash after some period of time, but the results are still consistent with results found in OpenFOAM. Both frameworks give results that are in a comparable range with the analytical results.