average pressure of a volume area
 

hi foamers,

for a simulation of a channel flow I like to
calculate the average the pressure of a specific area.

For patch are simple, like this
(gSum(phi.boundaryField()[1]))
but when I got a cube, not a patch, in the channel ????.

Is there any opportunity to create a sphere like in setFields and
calculate the pressure value of this area?

best regards
sven