I'm solving an axsisymmetric problem: 6-degrees sektor with 2D mesh (1 cell in the theta-direction). Should I use cyclic or symplane boundaries?

It's safer to use cyclic boundaries for two reasons: 1. if you have swirl, you have to use cyclic; 2. since STAR solves velocity components in Cartesian coordinates, if x-y (u-v as velocity)is in the r-theta plane and z (w) is axis, you will have both u and v velocity components (then you have to use cyclics) unless you put your case between -3 and 3 degrees (or other positions where either u or v is zero).

Hi, I think that if the flow is swirling (The velocity component in the circumferential direction is not equal to zero), you should use cyclic boundary conditions. Otherwise, I believe that symmetric boundary conditions should be ok. Regards Allan