Numerical wave scenario research is becoming of increasing importance in the coastal engineering com- munity, mainly because of its resource-efficient and time-reducing advantages over physical experiments. The motivation for this thesis is given by a project for the assessment of a wave energy converter, for whose investigation a numerical tool is of need that can accurately reproduce non-linear waves. The goal of this work is to assess the ability of the weakly compressible SPH code DualSPHysics to fulfill this con- dition. In order to achieve this, the theory of the SPH method is first presented in detail, which allows to obtain a good understanding of its functioning and to classify its strengths and weaknesses. Later the convergence behavior of the method is critically analyzed by generating second-order Stokes waves with a flap-type wavemaker. It turns out that the code cannot converge against the analytical solution of the wave, and constant errors of about 5% are observed. Said error comprises a dominant phase error and a minor amplitude error. In detail, there are three contributors to the dominant phase error: an incorrect numerical velocity, an incorrect acceleration of the wave, and a gap between the wavemaker and the medium that is an artifact of the applied DBC boundary condition. The newly developed mDBC boundary condition can in DualSPHysics efficiently eliminate the latter cause of the phase error, while the lack of convergence against the analytical solution remains. However, it is also shown that the SPH method has the ability to converge against itself with rates of about O(h1.5), i.e. it converges against a wave calculated by a particularly fine solution. A sensitivity analysis showed that the number of particles within the kernel radius of the SPH interpolation expressed through the COEF H parameter, is critical for the wave quality: While its increase is positively correlated to a reduction of the errors of the wave phase, wave amplitude, and wave speed, the velocity profiles under the wave suffer from it. Interesting and unintuitive trends have also emerged for other parameters, such that it was for example found that a refinement of the temporal reso- lution has a negative effect on the wave quality. Finally, it is discussed how artificial diffusion terms in the momentum and mass equations affect the behavior of the energy conservation. Those terms are usually needed in the SPH method to keep the density and pressure fields stable. Of the investigated formulations the density diffusion treatment by Fourtakas et al. (2019) is found to be superior to the other methods. This formulation can satisfactorily preserve the energy as well as achieve an accurate approximation of the pressure fields. The damping behavior of said density diffusion formulation exhibits a diffusion term independent and constant decrease of the wave height over distance. In the vicinity of the wave maker, the crests of the wave became more pronounced and the troughs of the wave were weakened, which shows that the wave becomes fully developed only after about three to four wavelengths.     «

Numerical wave scenario research is becoming of increasing importance in the coastal engineering com- munity, mainly because of its resource-efficient and time-reducing advantages over physical experiments. The motivation for this thesis is given by a project for the assessment of a wave energy converter, for whose investigation a numerical tool is of need that can accurately reproduce non-linear waves. The goal of this work is to assess the ability of the weakly compressible SPH code DualSPHysi...     »