Mirror seeing in forced flow

In the case of a ventilated mirror, the seeing decreases showing a dependency on the Froude number

$$Fr = \frac{T U^2}{\Delta T g D}$$ (22)

The relationship derived by analyzing various experiments is:

$$\theta/\Delta T = 0.18 \; {Fr}^{-0.3}$$

The dependency on the Froude number suggests the influence of the mirror size. Thus larger mirrors should produce more seeing in the same conditions of ventilation.
 

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Figure 7:$\theta /\Delta T$ as a function of the Froude number for a ventilated mirror.
The line represents the function $\theta/\Delta T = 0.18 \; Fr^{-0.3}$

1998-07-05