Hello All -

I am trying to simply define the diffusivity properties of 5 different species for two different zones. I have decided using if loops is the most efficient. Everything appears to be in order, and the UDF hooks to fluent just fine, but when I attempt to begin iterating, I get "Floating Point Error: invalid number." I am not sure if fluent is even recognizing the coefficients I am putting in. Please Help!!! Cheers

#include "udf.h" DEFINE_DIFFUSIVITY(protondiff,c,t,i) {

real D; int zone_ID = THREAD_ID(t);

if (i == 1){

if (zone_ID==2)

{D = 2.03e-15;}

if (zone_ID==3)

{D =2.03e-15;} return D;} if (i == 2){

if (zone_ID==2)

{D = 8.91e-10;}

if (zone_ID==3)

{D = 9.90e-10;} return D;} if (i == 3){

if (zone_ID==2)

{D = 1.9285e-11;}

if (zone_ID==3)

{D = 2.03e-11;} return D;} if (i == 4){

if (zone_ID==2)

{D = 4.275e-11;}

if (zone_ID==3)

{D = 4.5e-11;} return D;} if (i == 5){

if (zone_ID==2)

{D =2e-15;}

if (zone_ID==3)

{D = 2e-15;} return D;} }

I am not shure but i think species numeration starts with 0 and not 1. Try 0..4 instead of 1..5 . And let the function always retun a value and not only if one of those "if" conditions is true.

Good luck

Thanks, Im going to try using else if, and at the end add a else => return D