Impacts of the near-shore landscape heterogeneity on the off-shore wind turbine efficiency

The efficiencies of off-shore wind farms are often affected by the near-shore landscape exhibiting sharp spatial heterogeneity, which may lead to non-uniformity on the momentum distribution, i.e., the formation of high/low momentum pathways (H/LMPs). To explore this issue, we conduct large-eddy simulations for off-shore wind farms in a neutral atmospheric boundary layer, where the near-shore landscape features spanwise heterogeneity composed of alternating strips of different roughness heights. We vary the off-shore distance (Ls) and explore the effects of H/LMPs on a single off-shore wind turbine at different spanwise locations. Although it is expected that as HMPs and LMPs mix, the momentum magnitude becomes more uniform when spanwise heterogeneity no longer persists in the off-shore region. Our results show that, within a certain range of Ls, the efficiency of the wind turbine in the HMP increases while that of the wind turbine in the LMP decreases as a function of Ls. This behavior is attributed to the decay of secondary flow structures along the streamwise direction in the off-shore region. This finding is crucial for understanding and utilizing the near-shore landscape heterogeneity to enhance the off-shore wind farm efficiency.