We have pointed out in several instances in this work that mirror seeing is a real outstanding issue for the performance of new generation telescopes. It is therefore of particular interest to investigate how CFD models may be used in this context. The parameterizations derived in the previous sections for the mirror seeing effects both with and without ventilation should be adequate for most practical design cases of a telescope/enclosure systems. There will occur, however, special cases in which the airflow on the mirror has particular characteristics which are not well represented by the theoretical and experimental assumptions taken in described above.
We have seen that the source of the mirror seeing effect is "concentrated" in a very thin layer close to the surface of the mirror. Therefore a comprehensive CFD model would require a very tiny resolution of the grid model near the surface, while keeping a good representation of all the larger structures surrounding the mirror and the telescope which determine the general flow characteristics. Such models would be costly and in fact unpractical, at least with the present state of the art. We will therefore propose a simplified approach.
The small height of the turbulent layer responsible of mirror seeing
also means that the turbulence profile is essentially a function of
surface flux and that conditions may be assumed to be horizontally
homogeneous. This suggests to propose a numerical
parameterization of the 
profile as a function only of surface flux and flow characteristics computed at one height from the surface. The purpose of the CFD model can then be limited to the computation of the general flow conditions above the mirror.
From the main parameters of the flow computed at, say,
1 cm from the surface (mean velocity, turbulent kinetic energy,
mean temperature and surface flux,
the local 
profiles are evaluated by a similarity model
adapted from the expressions (
) and (),
in which the friction velocity 
is replaced by an
equivalent velocity scale 
evaluated from
the turbulent kinetic energy e:
The 
profile is then computed as:
Following the interpretation of mirror seeing in conditions of
mixed/forced convection illustrated in fig. (page
), the
maximum of the 
profile is set at the interface between the
viscous-conductive layer and the fully turbulent flow.
This interface may be defined as the height at which the kinematic
viscosity of air 
and the eddy diffusivity for momentum
have the same value. Recalling expression
() we obtain:
For 
, 
is linearly interpolated to a zero value at the
surface.
