[Nicola Viscanti]

Good morning.
I need to write a UDF to specify direction-1 and direction-2 in a bend porous mean.
I cannot use UDF and so I need your help. I try to explain what UDF must do according with figure.

if z<0.977

Direction-1
x=0
y=0
z=1
Direction-2
x=1
y=0
z=0

else if -1.397<x<1.397

Direction-1
x=1
y=0
z=0
Direction-2
x=0
y=0
z=1

else if x>1.397

Direction-1
x=-(zi-0.9777)/sqrt((xi-1.397)^2+yi^2+(zi-0.977)^2)
y=0
z=(xi-1.397)/sqrt((xi-1.397)^2+yi^2+(zi-0.977)^2)
Direction-2
x=(xi-1.397)/sqrt((xi-1.397)^2+yi^2+(zi-0.977)^2)
y=0
z=(zi-0.9777)/sqrt((xi-1.397)^2+yi^2+(zi-0.977)^2)

else

Direction-1
x=-(zi-0.9777)/sqrt((xi-1.397)^2+yi^2+(zi-0.977)^2)
y=0
z=(xi+1.397)/sqrt((xi-1.397)^2+yi^2+(zi-0.977)^2)
Direction-2
x=(xi+1.397)/sqrt((xi-1.397)^2+yi^2+(zi-0.977)^2)
y=0
z=(zi-0.9777)/sqrt((xi-1.397)^2+yi^2+(zi-0.977)^2)

end if

xi, yi, zi are node coordinates

Thank you in advance.

Nicola

[`e`]

You can use the DEFINE_PROFILE macro to apply porous resistance direction vectors; see example 7 in the UDF manual. The programming language is ANSI C (you'll need to modify the syntax of your conditional statements). The cell centroid coordinates are available with "C_CENTROID(x,c,t);".