Parabolised model of the turbulent wake behind marine turbines

The extraction of hydrokinetic energy from ocean currents or tides involves the use of marine turbines generating turbulent wakes. The prediction of the wake characteristics is essential because the velocity deficit and increased levels in turbulence intensity dictate the interaction between turbines and any environment impact. A numerical methodology combining the parabolised Navier-Stokes equations with a modified actuator-disk model is presented. The main innovation of the modified actuator-disk model is that the flow is considered to be non-uniform downstream of the turbine. The numerical method is used to reproduce the experiments of Neary et al. (2013) and Mycek et al. (2014). The computational results show that the modification in the actuator-disk model aids in the reproduction of the experimental measurements. The simulations also show that increased levels in the ambient turbulence intensity cause a faster recovery in the turbulent wake, which agrees with experiments.