vortex shedding

Altug Basol

Hallo,

I am trying to solve a 2D flow around a rectangle in cartesian domain. I am using stream function vorticity formulation finite difference formulation. I have applied no-slip boundary conditions on the rectangle. My problem is I could not have vortex shedding when I increase the Re number. In my case the size of the vortexes at the back of the rectangle grow as I increase the Re number but shedding does not appear. Can I solve this problem if I increase the number of grids around the rectangle. I would be thankful if anybody can make me any suggestions.

Thank you very much

Altug