Environmental impact of tidal power in the Eastern Scheldt Storm Surge Barrier : Appendix C: CFD simulations of the Eastern Scheldt Barrier with and without tidal turbines : validation study and determination of discharge coefficients

As a step to estimate the impact on energy production and environment of tidal turbines placed in the Eastern Scheidt Storm Surge Barrier a Computational Fluid Dynamics (CFD) study has been carried out to study the flow around the turbines and the effect of the turbines on the discharge through the gate. This study is part of a broader project to assess the effect of the turbines in the barrier which is described in [1]. The CFD model focusses on a single gate opening of the Storm Surge Barrier and includes half of the adjoining gates on either side. In this 40 m wide Gate a 1.2 MW array existing of five Tocardo T2 tidal turbines have been installed in 2015. Transient computations of the barrier with and without the turbine array were carried out for a range of quasi stationary tidal phases. The turbines are resolved in detail as rotating equipment with the real-time rotation of the turbine blades (involving the displacement of the mesh nodes in an unsteady setting). Based on the prescribed rotational speed of the turbine, the torque and thrust is provided as output. Based on these computations an estimate of the effect of turbines on the discharge capacity of the storm surge barrier is given. This information will be used to parameterize the tidal turbines in the far-field hydrodynamic model of Eastern Scheidt estuary for a further assessment of the effect of tidal turbines on energy production and on the environment.