[leo1993]

Dear all,

I am relatively new to programming in c, and completely new in writing UDF's for Fluent. Now, I want to write an UDF that defines the thermal conductivity for the primary phase and the secondary phase. I am using the DEFINE_PROPERTY macro to do this. I have tried this in the following way:

/*********************************************************************
   UDF that simulates the correlation for the conductivity proposed by Shen et al.                                    
**********************************************************************/
#include "udf.h"

DEFINE_PROPERTY(cell_conductivity,cell,thread)
{
	/* Variable fluid properties for water-vapor subcooling @353.15 K as defined by Mills */
        real T_SAT 						= 373.15;
	real k_v 						= 24.8e-3;
	real k_l						= 0.674;
	real ktc_;
	/* Enhancement factor n, as proposed by Shen. Enhances the energy transportation in the two-phase region. */
	real n 							= 1.;
	
	Domain *subdomain_gas;
	Domain *subdomain_liq;
	int phase_domain_index_gas; 		
	int phase_domain_index_liq;
	Thread *gas;
	Thread *liq;
	real temp;
	
	subdomain_gas 					= Get_Domain(2);										/* retrieve pointer to primary phase domain */
	subdomain_liq 					= Get_Domain(3);										/* retrieve pointer to secondary phase domain */
	phase_domain_index_gas 			        = PHASE_DOMAIN_INDEX(subdomain_gas);				
	phase_domain_index_liq 			        = PHASE_DOMAIN_INDEX(subdomain_liq);
        gas 						= THREAD_SUB_THREAD(thread, phase_domain_index_gas);
        liq 						= THREAD_SUB_THREAD(thread, phase_domain_index_liq); 
	temp 					        = C_T(cell,thread);


  
	if (temp >= T_SAT){
		ktc_ = C_VOF(cell,liq) * k_l + C_VOF(cell,gas) * k_v;
	}
	else {
		ktc_ = C_VOF(cell,liq) * k_l + n * C_VOF(cell,gas) * k_v;
	}
	return ktc_;
}

The problem is the following. I am able to compile the code and to load it, but when I specify the user defined conductivity in the material properties, I receive a segmentation fault.
I would be very happy if someone could help me. Also, feel free to give any tips on programming if you like.

Cheers!