The low wind effect was studied by the means of 2D k − ω SST flow simulation. The optical path difference (OPD) was measured around the rectangular cross section corresponding to one arm of the structure holding the secondary mirror of a large telescope. OPD in the region downstream of the cross section revealed temporarily and spatially evolving oscillation with mean value of OPD of around -100 nm. A parametric study revealed a increase of 24 % and 48 % in OPD for the tilt of the cross section of 45◦ and 60◦ respectively. 28 % decrease of OPD was observed for the wind velocity increase from 1 to 3 m/s.     «

The low wind effect was studied by the means of 2D k − ω SST flow simulation. The optical path difference (OPD) was measured around the rectangular cross section corresponding to one arm of the structure holding the secondary mirror of a large telescope. OPD in the region downstream of the cross section revealed temporarily and spatially evolving oscillation with mean value of OPD of around -100 nm. A parametric study revealed a increase of 24 % and 48 % in OPD for the tilt of the cross section...     »