How to simulate a vortex with ANSYS-CFD?

[Lirock]

Hi,everyone:
I met a problem about CFD. In ANSYS-CFD,the command 'nrotat'is not avalid command. But if I want to simulate a vortex in a tube, which means there is a rotational speed at the inlet. How can I apply the rotational speed and get the vortex in the tube?

Thank you!

rock

 

[deveng100]

Couple all nodes to a single node in centre and give rotational velocity there.
It should do easily...
Dev