  This work aims at introducing model methodology and numerical studies related
to a Lagrangian stochastic approach applied to the computation of the wind
circulation around mills. We adapt the Lagrangian stochastic downscaling method
that we have introduced in [3] and [4] to the atmospheric boundary layer and we
introduce here a Lagrangian version of the actuator disc methods to take
account of the mills. We present our numerical method and numerical experiments
in the case of non rotating and rotating actuator disc models. We also present
some features of our numerical method, in particular the computation of the
probability distribution of the wind in the wake zone, as a byproduct of the
fluid particle model and the associated PDF method.
