[Alice_1994]

Hi, everyone.

I am doing a meandering open-channel simulation using VOF and RSM.
This meandering channel has four wavelengths, since it has the same geometry for each wavelength, I chose to only model one wavelength and set the streamwise inlet and outlet for periodic boundary conditions.

But there is a problem came across when I was trying to set the periodic boundary conditions in Fluent meshing. The error message said 'Cannot find a face zone matched with flow-inlet using the shift: ( 680.00 0.00 0.00 ). Try non-auto methods and/or adjust these parameters.' However, when I tried manually picking the periodic and reference surface, it still got the same error message.

Here are the boundary conditions I used:
1) flow inlet: mass flow inlet
2) flow outlet: pressure outlet
3) top outlet: pressure outlet
4) other: walls

I have tried many ways but am still not sure what caused this. However, when I tried to set the side walls for periodic boundaries, it worked. My guess is that in Fluent meshing, the inlet and outlet boundary could not be set as periodic boundary conditions, is that right? Then should I use another meshing software to achieve an identical mesh at the inlet and the outlet?

Many thanks for the help~