Efficient modelling of sand wave behaviour [Powerpoint Presentation]


Berg, Joris van den and Damme, Ruud van (2004) Efficient modelling of sand wave behaviour [Powerpoint Presentation]. In: NCK dagen, 18 en 19 maart 2004, Yerseke, The Netherlands.

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Abstract:Sand waves form a pattern of more or less parallel ridges. The wave length is about 300 meters and the height up to 10 meters, which is a considerable amount of the total water depth. Sand waves migrate with speeds of about 10 meters per year. Information on their behaviour is valuable: the larger part of the south of the North Sea bottom is covered with sand waves and there are plans to use this region for sand extraction, the placement of wind turbines and even the construction of an artificial island. Knowledge of the implications of such plans is needed to make decisions about them.

The currently used models that describe sand wave behaviour, try to incorporate the complete physics of both the tidal flow and the sand transport. Especially the flow calculation is very time consuming. For this reason, only the effect of sine formed disturbances has been investigated. Using this approach the occurrence of sand waves can be predicted. The predicted waves are all equal in size and shape and there is no (non-trivial) dynamic behaviour.

In reality, however, the amplitudes and wave lengths of natural sand waves do vary in space and time. The reasons for this are not yet theoretically understood.

In order to predict the full dynamic behaviour in 2D, a more efficient technique to predict the development of sand waves is needed. The goal is to find a model combined with a calculation method that is applicable to arbitrary initial conditions. This in order to be able to investigate whether irregularities in the initial conditions could be the cause of variations in sand wave patterns found in nature. An added benefit of such a model is that it can be used to predict the effect of large real life disturbances caused by human interference, like e.g. dredged channels, dams and artificial islands. These disturbances are usually not harmonic. Although thorough validation is still work in progress, a preliminary model with very promising results has now been found.
Item Type:Conference or Workshop Item
Additional information:Nederlands Centrum voor Kustonderzoek
Electrical Engineering, Mathematics and Computer Science (EEMCS)
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Link to this item:http://purl.utwente.nl/publications/60427
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