Problems about streamline in the axial diffuser
 

Hi, all.
This is my simulation of one centrifugal compressor. The BC of inlet is 1 atm for total pressure, 288.15 K for total temperature, axial direction for flow direction, and the BC of outlet is 3.4 atm for static pressure. The rotating speed of impeller is 28000 rpm.
When I checked the results in the view of B2B in CFD-post, I found the streamline in the axial diffuser was curly (the right one)while the upstream streamline in the radial diffuser (the left one )looked normal. Has anyone got this problem before?

Thank you for reading my post.
http://v1.freep.cn/3tb_1405280048269wc5512293.png
http://v1.freep.cn/3tb_140528004825y1h5512293.png

Do you mean the ripples in the streamlines?

This could be a numerical artifact:
* Rerun with a finer mesh
* Converge tighter
* Better mesh quality

and see if it goes away.

OR it could be real. Turbulence transition looks somewhat like that.