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The main results from the measurements are given in the figures found in the next pages, as a function of the distance from the edge of the slit.

Some measurements were taken along the center of the slit, others halfway to the left side, as it was remarked that flow and turbulence were often stronger along the sides than along the slit mid-line.

The 3.6-m dome, even with the slit facing the wind, acts as an efficient wind shield in terms of mean flow velocity. Nevertheless, the slit is the cause of velocity fluctuations inside the dome, which are larger than in the original atmospheric turbulence. This dome induced turbulence has a mean scale of the order of the the slit width and a peak frequency in the range 0.3 to 1 Hz. In proximity of the slit this effect causes also fluctuations of the dynamic pressure term that are larger than in the free atmosphere, particularly in the frequency range above 1 Hz where they might directly affect the tracking behavior of an hypothetic telescope whose top structure would come closer to the slit than the present telescope. Further inside the dome, because of the large decrease of mean velocity the amplitude of pressure fluctuations is largely below the situation in the free flow.

Figure: Measurement locations in the 3.6-m dome.







Lorenzo Zago,, Sun Feb 26 22:57:31 GMT+0100 1995