Simple models for cross flow turbines

Using a high order discontinuous Galerkin numerical method with sliding meshes, we simulate one, two and three bladed cross-flow turbines to extract statistics of the generated wakes (time averaged velocities and Reynolds stresses). Subsequently, we compare the wakes resulting from simple models (a circular cylinder and an actuator disc) to the time averaged cross-flow turbine wakes. Additionally, we provide results for a reduced order model based on dynamic mode decomposition (Le Clainche and Ferrer, Energies, 11(3), 2018, [1]). Whilst simplified models find difficulties in capturing wake asymmetries characteristic of cross-flow turbines, our proposed reduced order model captures mean values and Reynolds stresses with good accuracy, showing the potential of the last technique to speed up the simulation of cross-flow turbine statistics.