Formation, development and instability of the vortices system are observed visually by means of Mach-Zehnder interferometer. A lazer source is used for the optical image of the formed vortices in a variable temperature field.
The investigation is conducted for a group of two-dimensional circular models at a constant Strouhal number of 5000. The excellent agreement, exhibited by the results provided by the observed cases; give an accurate and full description for the evaluation of the flow structure behined the cylinder. It is concluded that the influence of the temperature field is to
retard the evolution of the near-wake, as well as moving the location of the separated shear layers dowstream. The observed region by the lazer aided-interferometer reveals a good estimation of the bulk flow temperature field behined the cylinder.