vortices do not move
 

Hello
I am simulating a transient flow around a cylinder (the classical problem) with ansys-cfx12. the problem information is as follow:
cylinder diameter: 5 cm
air flow speed: 10 m/s
time step: 0.05 s
duration: 1 s
There are two main problems:
1. I can see to symmetrical vortices behind the structure in the shadow region in cfx post by velocity countors or by velocity streamline but unfortunately the vortices are steady in position and do not move by changing time step (I also have change the velocity to 20 m/s but the vortices didnt move any more)
2. CFX did not calculate helicity and i can not draw vortex core regein any more
I hope that there whould be anyone to solve my problems.

How many mesh cells along the cylinder?

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