Hi I am a CFD newbie. Just learn MAC method from a CFD text. I trying to solve for the velocity profile in a rigid hollow pipe.

How do you solve for pressure with G-S method on the boundry if it is require the pressure points outside of the domain is required?

Would you make different assumption to solve the pressure at the inlet boundry form the boundry at the wall of the pipe?

Any help is appreciated.

Assume P(0,j) is near to P(1,j), with the former being ghost point pressure, and P(1,j) is the one at the first inner mesh center. There must be some relations regarding P(0,j)and P(1,j),and possibly, P(2,j), from boundary condition of P, or by applying corresponding momentum equation at the BC middle way between p(0,j) and p(1,j). These relations can be incorprated in G-S method for pressure.