I;m trying to set an inlet and outlet boundary conditon on 2 faces of a cube. however the faces are not plit up,the surface of the volume is considered to be all one face. so i want to use a UDF to set where z=0 to be an inlet with a velocity of 10 and where z=20 to be a outlet pressure=0. Is using a UDF the right way to do this? i know how to use c, but im not sure how i would really go about doing this.

I suggest to make each face a single boundary surface in Gambit. Then there will be no need for this UDF.

how would i do that, its all one face. say i had a cube that was all one suface face, no edges. how would i do what you said

thanks