|The Performance Assessment of Wave and Tidal Array Systems (PerAWaT) project, launched in October 2009 with £8m of ETI investment. The project delivered validated, commercial software tools capable of significantly reducing the levels of uncertainty associated with predicting the energy yield of major wave and tidal stream energy arrays. It also produced information that will help reduce commercial risk of future large scale wave and tidal array developments.
This deliverable demonstrates the functionality of an actuator disc model of a tidal turbine, which is performing under Basin Scale conditions with mesoscale tidal flows to create three-dimensional unsteady Reynolds Averaged Navier-stokes (uRANS) simulations.
The aim of this deliverable is to demonstrate the functionality of an actuator disc model of a tidal turbine, which is performing under BasinScale conditions with mesoscale tidal flows. The work therefore falls within the category of “turbine modelled/farm resolved” three-dimensional unsteady Reynolds Averaged Navier-stokes (uRANS) simulations. By averaging the results from these tests, the output can be used in the creation of shallow water equations, representing models of turbines, which are incorporated into basin scale models in WG2 WP3. By employing a uRANS approach, the calculation time can be much faster than if a blade-resolved approach was taken. Ultimately, in environments with significant anisotropic turbulence, a Large Eddy Simulation (LES) would be employed instead. For the purpose of this deliverable, avoiding otherwise extremely large computational costs associated with LES, a more isotropic tidal flow environment has been considered justifying the application of the cheaper uRANS approach involving a k-ε turbulence model. As a result, the Sound of Islay tidal environment has been chosen as a suitable test bed for a tidal array for this investigation.
In this report, the development, testing and validation of a mesoscale, three-dimensional tidal channel model, with the addition of an Actuator Disc model, is detailed. The modelling work uses the computational fluid dynamics software Code Saturne, with unsteady Reynolds-averaged Navier-Stokes equations resolving the turbulent tidal flow, including the interactions with the tidal farm, which is represented as a set of Actuator Discs on the local flow.