Neumann Pressure Boundary Condition with UDF
Dear all, I wonder if someone is able to give me an UDF coding example to force a Neumann b.c. to the pressure field on a pressure outlet, I mean:
dp/dn = 0 where n is the normal of a "pressure outlet" b.c. Thanks for your attention. Balder 
Hello,
I am stuck with the same problem except the fact that I want to implement du/dx=0 for a laminar pipe flow at the outlet(fully developed condition). Have you got any work around for your problem so far? 
Even I've the same problem, haven't got much help, how about you guys. The average static pressure=0 is the nearest matching BC. But I am not sure whether it serves any purpose.

Why do'nt you use an outflow bc (if u dont have backflow)? this bc sets both dp/dn=0 and dv/dn=0 automatically. if you have backflow through your boundary, then these Boundary Conditions make the problem illposed.

Maintaining static pressure=0 will get you the neumann boundary condition.
I confirmed it with the Ansys CFX tech people. thank you all..! 
I have the same problem with Temperature at the inlet for compressible flow.
adiabatic: dT/dx=0 
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IDo you meant CFX or FLUENT?:rolleyes: 
I have written the UDF for convective B.C using DEFINE_PROFILE.....Can any1 tell me how to apply it at the outlet?

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