[8cold8hot]

My aim is to modify the epsilon equation in the realizable k-epsilon turbulence model.

This is my UDF code:

#include "udf.h"
#include<math.h>

#define C2 1.9	/* The original value of coefficient  */

DEFINE_SOURCE(source_realizable_e, c, t, dS, eqn)
{
#if !RP_NODE
	real fk = 0.5;	/* The fraction of unresolved kenetic energy to the total */
	real fe = 1.0;	/* The fraction of unresolved rate of dissiptation to the total */
	real source;
	
	real k_temp = C_K(c,t);
	real e_temp = C_D(c,t);
	
	source = -(fk/fe-1)*C2*e_temp*e_temp/(k_temp+sqrt(0.001003/998.2*e_temp));
	dS[eqn] = 0.0;
	
	return source;
#endif	
#if RP_NODE
	dS[eqn] = 0.0;
	return 0.0;
#endif
}

DEFINE_PRANDTL_D(Prandtl_realizable_e, c, t)
{
#if !RP_NODE
	real fk = 0.5;	/* The fraction of unresolved kenetic energy to the total */
	real fe = 1.0;	/* The fraction of unresolved rate of dissiptation to the total */
	
	return 1.2*fk*fk/fe;
#endif

#if RP_NODE
	return 1.2;
#endif
}

May someone tells me that if I uses the right compilation directive? I think the source term shall be added in the host process, is that right?


Thank you in advance!

[upeksa]

I don't really know what do you want to do, but try something like this

#include "udf.h"
#include<math.h>

#define C2 1.9 /* The original value of coefficient */

DEFINE_SOURCE(source_realizable_e, c, t, dS, eqn)
{
#if !RP_HOST
real fk = 0.5; /* The fraction of unresolved kenetic energy to the total */
real fe = 1.0; /* The fraction of unresolved rate of dissiptation to the total */
real source;

real k_temp = C_K(c,t);
real e_temp = C_D(c,t);

source = -(fk/fe-1)*C2*e_temp*e_temp/(k_temp+sqrt(0.001003/998.2*e_temp));
dS[eqn] = 0.0;

return source;

#endif
}

DEFINE_PRANDTL_D(Prandtl_realizable_e, c, t)
{
#if !RP_HOST
real fk = 0.5; /* The fraction of unresolved kenetic energy to the total */
real fe = 1.0; /* The fraction of unresolved rate of dissiptation to the total */

return 1.2*fk*fk/fe;
#endif
}

I think that the host process has nothing to do with your code.

Cheers