  We describe a generalization of the Coupled Wake Boundary Layer (CWBL) model
for wind-farms that can be used to evaluate the performance of wind-farms under
arbitrary wind inflow directions whereas the original CWBL model (Stevens et
al., J. Renewable and Sustainable Energy 7, 023115 (2015)) focused on aligned
or staggered wind-farms. The generalized CWBL approach combines an analytical
Jensen wake model with a "top-down" boundary layer model coupled through an
iterative determination of the wake expansion coefficient and an effective wake
coverage area for which the velocity at hub-height obtained using both models
converges in the "deep-array" portion (fully developed region) of the
wind-farm. The approach accounts for the effect of the wind direction by
enforcing the coupling for each wind direction. Here we present detailed
comparisons of model predictions with LES results and field measurements for
the Horns Rev and Nysted wind-farms operating over a wide range of wind inflow
directions. Our results demonstrate that two-way coupling between the Jensen
wake model and a "top-down" model enables the generalized CWBL model to predict
the "deep-array" performance of a wind-farm better than the Jensen wake model
alone. The results also show that the new generalization allows us to study a
much larger class of wind-farms than the original CWBL model, which increases
the utility of the approach for wind-farm designers.
