Large eddy simulation of a utility-scale vertical-axis marine hydrokinetic turbine under mobile bed conditions*

We present a coupled large-eddy simulation (LES) and bed morphodynamics study to explore the impact of mobile bed flume and sediment dynamics on the performance of a utility-scale vertical-axis marine hydrokinetic turbine (VAT). This study also aims to gain insight into the impact of the VAT wake flow on the sediment dynamics and scour development in the waterways, thus addressing the environmental impact of such turbines. To that end, we analyzed the wake recovery, power production, and sediment dynamics of the system at various tip speed rations. Various components of the turbine, waterway, and sediment layer are captured using the geometry-resolving immersed boundary method. The findings of the study revealed the intricate turbulent wake flow field of the VAT and its footprint on the mobile bed in the form of 3D sand waves throughout the channel bed.