Vortex Shedding in low Reynold's Number 2D airfoil
 

Hi

I was simulating flow on a low Reynold's Number airfoil, eppler387. I have taken the Re No. as 60000 and angle of attack 4 degrees. In these conditions vortex shedding is supposed to occur. I simulated the problem using 3 Eq turbulence model K-Kl-w keeping laminar kinetic energy 1e-6, turbulence intensity 1% and turbulence length scale 0.0008. The results were good and I got behavior that was expected. However when I change to the 4 eq model Transition SST, I didnt
get the expected vortex shedding. As I do not have a lot of background knowledge on the subject I was wondering what might be the reason of such behavior?

http://i57.tinypic.com/ip0dxy.jpg
3 Equation Model

http://i62.tinypic.com/6ih3ie.png
4 Equation Model

you should go through the basics books of cfd you will get your answer or also you get it in fluid dynamics books..