The Pentland Firth is believed to be one of the most promising locations for the extraction of energy from tidal streams, and so is one of the sites being studied as part of the PerAWaT project commissioned by the Energy Technologies Institute. In this paper we investigate numerically the hydrodynamics of the Pentland Firth using a discontinuous Galerkin, depth-averaged shallow flow model. Drag exerted on the flow by a tidal turbine (or array of turbines) is modelled by a local enhancement to the bed friction in the shallow flow model. The turbine drag and the inviscid limit to the useful energy which may be extracted are calculated using linear momentum actuator disc theory, using realistic values of wake induction factor and blockage ratio. The predictions are compared with esults from simplified models of energy extraction from a tidal channel available in the literature.
