  We evaluate the accuracy of the actuator line model (ALM) approach by
performing simulations for the NREL~5~MW wind turbine in uniform inflow using
three large eddy simulation codes. The power and thrust coefficients obtained
using the three codes agrees within $1\%$ when the grid spacing $\Delta_{\rm
grid} \le 5.25$~m, and are cross-validated against blade element momentum (BEM)
theory. We find that the results of ALM converge towards BEM theory without the
need for tip correction when the numerical resolution is increased. For
$\Delta_{\rm grid}=0.98$~m the difference between the power and thrust
coefficient obtained using ALM and BEM is $4.5\%$ and $2.1\%$, respectively,
although we note that no absolute convergence between ALM and BEM can be
obtained as both models use different assumptions, such as the use of a force
projection method in the ALM. The difference in the local axial and tangential
forces along the blades obtained from ALM simulations using $\Delta_{\rm grid}
= 1.97$~m and $\Delta_{\rm grid} = 0.98$~m can be as large as $10\%$. The
effect of the number of actuator points on the obtained turbine power and
thrust coefficients is limited as the results converge when the spacing between
the actuator points is about three times the grid spacing. This insight on the
required number of blade points can be used to improve the efficiency of
actuator line simulations.
