"enum" in UDS stuff
 

What is the meaning of the following codes:

---------------------
enum
{
P1,
N_REQUIRED_UDS
};

----------------------

***********************************

----------------------

DEFINE_ADJUST(p1_adjust, domain)
{

/* Make sure there are enough user defined-scalars. */
if (n_uds < N_REQUIRED_UDS)
Internal_Error("not enough user-defined scalars allocated");

}

----------------------

enum
{
P1,
N_REQUIRED_UDS
};

P1=0,N_REQUIRED_UDS=1; see c language primers for enum usage

n_uds is a macro to get the number of uds that have been allocated.

Thanks.
Anyway what's the point of using enum?

Plz check the below code what's the "sg.h" for???

I have 2 UDS. I wrote their code in separate files. Should I put their names in both files?


******************************
#include "udf.h"
#include "sg.h"

enum
{
ELECT_CHARGE_UDS,
CARB_CHARGE_UDS,
N_REQUIRED_UDS
};

static real ACT_AREA=1;
static real REF_EXCH_CURR_A=1;
static real MW_H2=1;
static real REF_CONC=1;
static real BETA=1;
static real ALPHA=1;
static real NO_ELEC=1;
static real EQU_POT_A=1;
static real FARADAY=1;
static real UNI_GAS_CONS=1;
static real STOCH=1;
static real RXN_RATE_A;
static real Z;
static real ZZ;
static real ZZZ;
static real source;

DEFINE_ADJUST(ELECT_CHARGE_UDS, domain)
{

if (n_uds < N_REQUIRED_UDS)
Internal_Error("not enough user-defined scalars allocated");
}

DEFINE_SOURCE(ELECT_CHARGE_UDS,c,t,dS,eqn)
{
Z=ACT_AREA*REF_EXCH_CURR_A*pow(((C_YI(c,t,0)*C_R(c ,t)/MW_H2)/REF_CONC),BETA);

ZZ=exp((ALPHA*NO_ELEC*FARADAY*(C_UDSI(c,t,0)-EQU_POT_A))/(UNI_GAS_CONS*C_T(c,t)));

ZZZ=exp((1-ALPHA)*NO_ELEC*FARADAY*(EQU_POT_A-C_UDSI(c,t,0))/(UNI_GAS_CONS*C_T(c,t)));

RXN_RATE_A=Z*(ZZ-ZZZ);

source=(-STOCH/(NO_ELEC*FARADAY))*RXN_RATE_A;

dS[eqn]=0;

return source;
}

DEFINE_DIFFUSIVITY(ELECT_CHARGE_UDS,c,t,0)
{
return 1;
}