It is difficult, using simple models, to model the effects of strong nonlinear waves and breaking waves on coastal and offshore structures. Here, the rasInterFoam CFD code, part of the OpenFOAM library, is used to validate against experimental data for a 3D problem. The experimental data consists of free surface elevation time-series from the impact of non-linear waves on a cylindrical column in shallow water. It is found that results obtained even from relatively coarse meshes can give useful results, with the CFD model able to reproduce the shape and wave spectrum of a focused wave group to reasonable accuracy. It is also found that smaller meshes provide greater accuracy, but that the computational cost of this accuracy is not always justified. It is shown that the computational expense of the method is not prohibitive of its use as a design tool.
As sea levels change around the world, it is becoming necessary to reassess the performance of coastal structures to ensure that they are still robust and fit-for-purpose under the new water level and wave conditions. Alongside this need to revalidate the design of critical coastal infrastructure such as sea walls and coastal flood embankments, the performance and capability of computers has continued to increase. This means that computational methods such as Computational Fluid Dynamics (CFD), which previously have been considered to be too computationally expensive for this type of problem, are becoming increasingly practical tools for the assessment of loading on coastal and fluvial structures. It is important to consider these potentially more accurate methods when reassessing the performance of existing structures as, even if the performance of a structure has reduced, by using methods which are potentially more accurate than the original assessment tools, such a structure may still be considered fit-for-purpose.
