Hi I try to interpret the UDF example which is in the UDF help of fluent about DEFINE_HET_RXN_RATE, but I have syntax errors (line 2 and 3) and "structure reference not implemented" (line 9,10,11). This example specifies an Arrhenius type reaction rate for heterogeneous reactions. Anybody could help me? Thank you in advance.
#include "udf.h"
static const real Arrhenius = 1.e15; static const real E_Activation = 1.e6; #define SMALL_S 1.e-29
DEFINE_HET_RXN_RATE(arrh,c,t,hr,mw,yi,rr,rr_t) {
Domain **domain_reactant = hr->domain_reactant;
real *stoich_reactant = hr->stoich_reactant;
int *reactant = hr->reactant;
int i;
int sp_id;
int dindex;
Thread *t_reactant;
real ci;
real T = 1200.; /* should obtain from cell */
/* instead of compute rr directly, compute log(rr) and then
take exp */
*rr = 0;
for (i=0; i < hr->n_reactants; i++)
{
sp_id = reactant[i]; /* species ID to access mw and yi */
if (sp_id == -1) sp_id = 0; /* if phase does not have species,
mw, etc. will be stored at index 0 */
dindex = DOMAIN_INDEX(domain_reactant[i]);
/* domain index to access mw & yi */
t_reactant = THREAD_SUB_THREAD(t,dindex);
/* get conc. */
ci = yi[dindex][sp_id]*C_R(c,t_reactant)/mw[dindex][sp_id];
ci = MAX(ci,SMALL_S);
*rr += stoich_reactant[i]*log(ci);
}
*rr += log(Arrhenius + SMALL_S) -
E_Activation/(UNIVERSAL_GAS_CONSTANT*T);
/* 1.e-40 < rr < 1.e40 */
*rr = MAX(*rr,-40);
*rr = MIN(*rr,40);
*rr = exp(*rr); }
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