HOw to set the axis boundary conditions at the fastran cfd software. in the given B.C. TYPE. there is not the axis B.C on the general B.C. menu. BuT in the demo validation examples of the attached PDF files, the grid around HYPERSONIC missile include the axis, so it must be able to deal with the axis b.c. I try to define the aixs b.c as symmetry b.c .it run well .but i can't certain it. who can give me some explatation and suggest. thanks in advance

You can also use an extrapolated outlet boundary condition on a degenerated edge (advice from CFDRC). If the axis is a true line of symmetry then symmetry bc is obviously the way to go,but mostly it isn't. So then extrapolated outlet bc works fine. The pre-processor defaults to a wall bc, which is obviously not correct.

THANKS I CHECK the result in tecplot, as you said, the symmetry B.C at a axis (half body grid) is not correct. the pressure distribution is not regular. so i try to define it as you suggest. ok, i will try .thanks