whats the trick to access to second layer of patch neighbors in groovyBC?
 

i want to use an expression on outlet so that the pressure on the patch be to say 100000 less than internalField,
But for more smoothness its good to have access and participate second layers of neighbors in expression too.
How can do it?is it possible or not(with or without groovyBC)?

Not possible in groovyBC. And hard to do in C++ (part of the problem is that "second layer of cells" is only well-defined for a pure hex-mesh and even then you have corner-cases ... on the corners)

thanks.
what does "corner-cases" mean?

:D what interesting site! google was filtered some days ago!;)
but I mean what corner cases may occur,in what sense?

Draw a regular grid with a corner (concave and convex) on a piece of paper and think what the second layer of cells is. In one case you have cells from the first layer in the second layer. In the other case there are cells missing that should have an influence. And that is an easy case

yes you right,that issue is for one or three cell but may be somewhat hard to write a program that realizes it but I have a thesis that have done it,I'll try to do this maybe some months later(after being light my works)and share!
now I think gradientExpession "-50000" for example works fine enough(acceptable).