UDF for variable porosity
 

hi I want to define the porosity to vary along the bed height

i am working with fluent6.1 i read the manual, but cant find how to define/ write UDF for variable porosity

My problem is relatively simple

bed has three layers of different depths each having porosities 0.27, 0.3 and 0.35 respectively

i only found i had to use DEFINE_PROPERTY macro what next

anyone having some idea, pl reply soon. thanks in advance