When accessing site conditions for wind turbines, it is typical to apply steady-state “RANS” models to predict average quantities like turbulence intensity and wind shear. However, it may also be helpful to investigate unsteady effects like wake meandering, unstable thermal stratification, and flow separation due to complex terrain. High-fidelity modelling like “LES” is needed to predict unsteady flow phenomena, but it comes at a high computational cost. Letzgus, Guma, and Lutz (2022) simulate the unsteady flow at a complex wind turbine test site using a hybrid RANS-LES model to overcome this.

Letzgus, Guma, and Lutz (2022) first apply the hybrid model to separately investigate the unsteady effects of a forested escarpment, thermal stratification, and a wind turbine. Subsequently, all effects are combined to simulate an actual 5-minute period observed at the test site. The paper, therefore, presents a practical method for simulating the unsteady flow relevant to wind turbines and provides flow visualisation to help our understanding.

Letzgus, Patrick, Giorgia Guma, and Thorsten Lutz. 2022. “Computational Fluid Dynamics Studies on Wind Turbine Interactions with the Turbulent Local Flow Field Influenced by Complex Topography and Thermal Stratification.” Wind Energy Science 7 (4): 1551–73. https://doi.org/10.5194/wes-7-1551-2022.