SU2 V7 periodic BC result not make sense
 

Dear all，
I am trying to use a tandemcylinders testcase to test SU2 V7.However , the result seems not to make sense. I set periodic BCs in the .cfg file like this:

% Periodic boundary marker(s) (NONE = no marker)
MARKER_PERIODIC= ( Y0, Y18, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.18, 0.0 )
KIND_ADAPT= PERIODIC

and set dual-time-stepping-2nd-order in TIME-MARCHING.

The Q-criterion seems the periodic BCs operate more like a symmetry wall, I wonder if it is my fault or the code have problem in 3d unsteady simulation with periodic walls.

Any help will be appreciated.

Thanks,
Shihe Jia

Q-criterion
 

i put the figure here