Numerical Modelling of Sand Wave Fields in the North Sea using Delft3D FM
After finishing my graduation project on the numerical modelling of sand waves at Deltares I am now continuing my research in a PhD position. Sand waves are large scale dynamic bed forms, which are found at sites throughout the world. The prediction of sand wave dynamics is relevant for the depvelopment of (amongst others) offshore wind farms in those areas. Sand waves in the North Sea are several meters in height and have a length of several hundreds of meters. They migrate at a rate of a few meters per year and in the direction of migration they can have a relatively steep slope. This sudden change in bed level can pose a threat to among others foundations, cables and pipelines. The scale of these sand waves (and especially the steep slope) relative to the scale of the system (the sea/ocean), makes numerical modelling of these bed forms rather difficult. The newly developed Delft3D FM model may offer solutions to some of these problems. The use of unstructured grids and increased numerical efficiency creates new opportunities to incorporate both the (smaller scale) sand wavesand the (large scale) underlying bathymetry as well as 3 dimensional hydrodynamics in the model.
During my graduation project I compared the Delft3D FM and Delft3D 4 models for a simplified 2DV sand wave set-up. The results were comparable between the models. Subsequently the Delft3D FM model was used to simulate sand wave dynamics at a location in the North Sea in 2DV and 3D setting. Although the predictive capacities of the model need to be improved the results were promising. During my PhD research I will further explore the influence of 3D effects on sand wave dynamics using Delft3D FM. Furthermore, tools will be developed to predict sand wave dynamics and the impact of offshore activities on sand waves in a computationally efficient way.
