  In this work the accuracy of the Actuator Line Model (ALM) in Large Eddy
Simulations of wind turbine flow is studied under the specific conditions of
very coarse spatial resolutions. For finely-resolved conditions, it is known
that ALM provides better accuracy compared to the standard Actuator Disk Model
(ADM) without rotation. However, we show here that on very coarse resolutions,
flow induction occurring at rotor scales can affect the predicted inflow angle
and can adversely affect the ALM predictions. We first provide an illustration
of coarse LES to reproduce wind tunnel measurements. The resulting flow
predictions are good, but the challenges in predicting power outputs from the
detailed ALM motivate more detailed analysis on a case with uniform inflow. We
present a theoretical framework to compare the filtered quantities that enter
the Large-Eddy Simulation equations as body forces with a scaling relation
between the filtered and unfiltered quantities. The study aims to apply the
theoretical derivation to the simulation framework and improve the current
results for an ALM, especially in the near wake where the largest differences
are observed.
