I have been reading papers now for the last few weeks and I have taken from all the information so far that vortex shedding from a cylinder happens periodically for reynolds numbers anywhere between 90 and 1000. It seems to me that there is no actual way of defining the specific parameters of the shedding vortices in the region of sub-critical flow where the reynolds number is less than 1.5×105. My main question is, does the cylinder still shed vortices at all when the reynolds number is around 1×104? I know that the Strouhal number can be used to find the shedding frequency of vortices for a given diameter and wind speed, but most of the time the Strouhal number is estimated using the Reynolds number and if the Reynolds number is higher but not super-critical can this relationship still be used? I am currently testing a cylinder in a wind tunnel with a diameter of 16cm with wind speeds ranging from 3-10m/s. This gives me a reynolds number ranging from 3.2×104 to 1.0×105. I have researched that vortex shedding has been known to occur at these Reynolds numbers, if it is that lamp posts (for example) do vibrate due to the shedding of vortices the Reynolds numbers would be of the same order and would suggest that t does indeed occur. Here's a nice picture http://img63.imageshack.us/img63/119/82450048.jpg [Broken] So in case 4 here is that also classified as vortex shedding but it's just not a Karman vortex street? Also how would the situation vary if a cuboid (square cylinder) was used?