Gradient of species mass fraction
 

hi guys,

I am solving a combustion problem involving ch4 (2 step model), and need the gradient of the species mass fraction for postprocessing. A simple UDF is used to extract the date with the following macro: C_YI_G(c,t,i). However, FLUENT compiles the UDF only for i = 0. When i is 1, 2, 3, or 4, the UDF does not compile. I get an error message instead. Any suggestions on how to solve this problem?

for 2step CH4 reaction you have 6 species. so for i=0-4 you can access to C_YI_G. for i=5 which refer to N2 you cant access to its gradient because its mass fraction calculated by algebraic equation not transport equation.

type in the console the following commands:
solve>set>expert
reply yes to question keep memory from being freed?
define>models>species
reply yes to question save-gardients?