Improved coupling between an atmospheric LES and an aeroelastic code for the simulation of wind turbines under heterogeneous inflow

Abstract. Wind energy simulations face a central challenge of coupling length scales, ranging from wind fields spanning hundreds of kilometers to the centimeter-scale relevant for turbine dynamics. To address this challenge, simulations employ fundamentally different tools. For instance, a large-eddy simulation tool simulates the large scales, while an aeroelastic code captures wind-turbine interaction at smaller scales. This study aims to examine a model framework developed to investigate wind turbine behavior in heterogeneous wind fields, such as those found in wind farms. The framework combines FAST and PALM, simulating realistic atmospheric wind conditions while providing high-quality turbine information. Computational efficiency is ensured through the use of a decoupled time step, resulting in an Actuator Sector Model within PALM and a blade-element momentum approach in FAST. Additionally, a wind speed correction is implemented to reduce errors that are caused by the necessary smearing of forces on the numerical grid of the atmospheric simulation when using actuator models to account for wind turbine effects. Results are evaluated through comparisons of different model setups and turbine measurements, including an assessment of a wake situation involving two turbines. Special attention is given to the number of blade elements in the turbine setup. The proposed model framework demonstrates good agreement with measurement data and performs well in the wake situation, used as representative of a highly heterogeneous wind field. It is applicable for studying turbine loads and power output in wake situations and other atmospheric wind fields.