co-axial pipes creation

Kush

Hello,

I am new to CFX.

I need to create two co-axial pipes. I extrude a smaller circle into the bigger pipe. What option should I choose so that the inner pipe doesn't merge in the bigger pipe but create a wall surface?

What I was trying till now is, to extrude the inner pipe as a frozen body. I am not sure if it would seperate both the pipe by a surface (wall).

Please help.

Thanks in advance, Kush