  Numerical models of the flow and wakes due to turbines operating within a
real-scale offshore wind farm can lead to a prohibitively large computational
cost, particularly when considering blade-resolved simulations. With the
introduction of turbine parametrizations such as the actuator disk (AD) or the
actuator line (AL) models, this problem has been partially addressed, yet the
computational cost associated with these simulations remains high. In this
work, we present an implementation and validation of an AL model within the
mesh-adaptive three-dimensional fluid dynamics solver, Fluidity, under a
unsteady Reynolds-averaged Navier-Stokes based turbulence modelling approach. A
key feature of this implementation is the use of mesh optimization techniques,
which allow for the automatic refinement or coarsening of the mesh locally
according to the resolution needed by the fluid flow solver. The model is first
validated against experimental data from wind tunnel tests. Finally, we
demonstrate the benefits of mesh-adaptivity by considering flow past the
Lillgrund offshore wind farm.
