udf doesn't work
 

Hi dear

I am trying to model solid carbon particals inside a cylinder using euler-euler model in fluent .The gas phase is o2 n2 co2 and the solid phase is c(s).In this simple model there is only one hetergeneousb reaction c(s) +o2 >co2. A udf is used to define the rate of this reaction. First the rate of the reaction is assumed to be kinetically controlled and this gave a result. Then it was assumed that the reaction is controlled by kinetics and diffusion of oxidant o2.The udf was compiled but it doesn't give results. So what is the wrong with this udf (attached).

your response is so appreciated,

Many thanks