question about udf for "particle surface reaction rate"
 

hi
I have a problem in understanding how Fluent calculates the particle reaction rate using UDF. the define macro for it is: DEFINE_PR_RATE
in the manul it says:
"Note that a DEFINE_PR_RATE UDF is not called with the coupled solution option, so you will need to disable the Coupled Heat Mass Solution option in the Discrete Phase Model panel when using it"
so if the calculation must be done in an Uncoupled manner how the effect of reaction of gas phase is calculated? I mean for this kind of reaction a source term must be in continuous phase. isnt it?
does any one know how specious concentration changes in continuous phase is accounted on reaction rate?
thanks alot