Hydrodynamic Modelling

EMEC has commissioned DHI to construct a numerical model of the Orkney Islands using the flexible version of MIKE 21 Flow Model FM. This will provide developers with detailed information on the water level, currents and waves at specific locations within the wave and tidal test sites. This model permits spatial varying resolution, so that the complex tidal channels and local topographic features that may influence the hydrodynamics can be sufficiently resolved. The calibrated model will be available for use by developers coming to test at EMEC.

Using the model, the simulated tidal flow pattern at Fall of Warness can be seen in the animation below.

The flow structure in Fall of Warness is further illustrated in the figure below, where the flow vectors are superimposed upon the current speed magnitude. The position of the eddy and the gradient in the current field is related to the local water depth and to the flow separation at Warness point.

A fully spectral model of the Orkney Islands is also being built using MIKE 21 Spectral Waves FM with special focus on the wave conditions at Billia Croo and at Fall of Warness. Using ADCP measurements at Fall of Warness this has highlighted the effects from the strong tidal stream on the wind-sea and swell wave climate due to wave-current interaction processes. This has been illustrated in the animation below.

Following the completion of the model it will be used to calculate the 20 year wave climate at both test sites for developers to use in device design.