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local thermal non equilibrium model in porous media

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Old   November 1, 2014, 16:00
Default local thermal non equilibrium model in porous media
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hi guys,im simulating a 2D transient problem,i have 9 different faces,i need to simulate 3 of these faces as a porous media using thermal non equilibrium model,and im using fluent6.3.26 and ansys fluent 15.0,fluent15 support the ltne model but its so heavy and slow,but fluent 6.3 is 2 times faster than fluent 15,my problem will take 17 days to reach the periodic state with fluent 6.3 (so 34 days with fluent 15.0),so i want to use fluent6.3 in order to reduce the time,going to the details of my problem i have to say that my porous solids are copper and steel and my working fluid is helium,and my solid walls are also copper and steel in non-porous zones,i have written some udf's and uds's to model the ltne in porous zones,but i dont know how to implement my codes,(specially the solid source term and solid diffusivity),i wonder if someone would help me,here is my code:
/********************************************/
/* user defined functions(UDFs) for LTNE MODEL */
#include "udf.h"
/******************************************/
/* Global definitions ***/
/************************************************** ***/
/****************** constants********************/
/* particle diameter (m)*/ #define dp 27.9e-6
/* porosity */ #define porosity 0.696
/* hydraulic diameter(m)*/ #define dh (porosity*dp)/(1.0-porosity)
/* c5,c6 copper thermal conductivity constants*/ #define c5 638.3495
/**********************************************/ #define c6 -0.0815
/* c7,c8 steel thermal conductivity constants*/ #define c7 1871.0374
/**********************************************/ #define c8 -0.5522
/****************** porous media:constants/functions for solid diffusivity******************/
#define COPPER_SOLID_DENSITY(T) 8933.0
#define COPPER_SOLID_THERMAL_COND(T) c5*pow(T,c6)
#define COPPER_SOLID_CP(T) 385.0
#define STEEL_SOLID_DENSITY(T) 7870.0
#define STEEL_SOLID_THERMAL_COND(T) c7*pow(T,c8)
# define STEEL_SOLID_CP(T) 447.0
/************************************************** *****************************/
/* Definition of user defined scalars (UDS) */
/************************************************** *********************/
enum
{
/*0*/ SOLID_TEMP, /*UDS for solid temperature*/

};
/************************************************** **********/
/** Diffusivity for UDS(SOLID_TEMP)*****************/
DEFINE_DIFFUSIVITY(UDS_diff_copper,cell,thread,i)
{
real source_copper,Ts,k_copper,rho_copper,cp_copper;
if(i==SOLID_TEMP)
{
Ts=C_UDSI(cell,thread,SOLID_TEMP);
k_copper=COPPER_SOLID_THERMAL_COND(Ts)*(1.0-porosity);
rho_copper=COPPER_SOLID_DENSITY(Ts)*(1.0-porosity);
cp_copper=COPPER_SOLID_CP(Ts);
source_copper=(k_copper)/(rho_copper*cp_copper);
}
else source_copper=0;
return source_copper;
}
DEFINE_DIFFUSIVITY(UDS_diff_steel,cell,thread,i)
{
real source_steel,Ts,k_steel,rho_steel,cp_steel;
if(i==SOLID_TEMP)
{
Ts=C_UDSI(cell,thread,SOLID_TEMP);
k_steel=STEEL_SOLID_THERMAL_COND(Ts)*(1.0-porosity);
rho_steel=STEEL_SOLID_DENSITY(Ts)*(1.0-porosity);
cp_steel=STEEL_SOLID_CP(Ts);
source_steel=(k_steel)/(rho_steel*cp_steel);
}
else source_steel=0;
return source_steel;
}
/************************************************** ***/
/* Helium properties ***/
/************************************************** ******/
/** Dynamic viscosity************************/
DEFINE_PROPERTY(helium_viscosity,cell,thread)
{
real mu,c1,c2,T;
c1=3.9928e-7;
c2=0.6853;
T=C_T(cell,thread);
mu=c1*pow(T,c2);
return mu;
}
/**Thermal conductivity of helium******************/
DEFINE_PROPERTY(helium_thermal_conductivity,cell,t hread)
{
real kh,c3,c4,T;
c3=2.3715e-3;
c4=0.7294;
T=C_T(cell,thread);
kh=c3*pow(T,c4);
return kh;
}

/************************************************** ******************/
/* Heat Transfer */
/************************************************** *****************/
/** Heat transfer coefficient between Solid and Gas *******************/
real HTC_solid_gas(cell_t cell,Thread*thread)
{
real Nu,Re,Pe,Pr,Us,hsf,asf,hv;
/* calculate superficial velocity*/
Us=sqrt(pow(C_U(cell,thread),2.0)+pow(C_V(cell,thr ead),2.0));
/* calculate Reynolds number*/
Re=Us*dh*C_R(cell,thread)/helium_viscosity(cell,thread);
/* calculate Prandtl number*/
Pr=C_CP(cell,thread)*helium_viscosity(cell,thread)/helium_thermal_conductivity(cell,thread);
/* calculate peclet number*/
Pe=Re*Pr;
/*calculate nusslet number*/
Nu=(1.0+((0.99)*(pow(Pe,0.66))))*pow(porosity,1.79 );
/* calculate HTC*/
asf=(4.0*porosity)/dh;
hsf=(Nu*C_K_L(cell,thread))/dh;
hv=hsf*asf;
return hv;
}
/** Heat source fluid **************************/
DEFINE_SOURCE(SRCE_fluid_heat,cell,thread,dS,eqn)
{
real hv,Ts,T,source;
hv=HTC_solid_gas(cell,thread);
Ts=C_UDSI(cell,thread,SOLID_TEMP);
T=C_T(cell,thread);
source=hv*(Ts-T);
dS[eqn]=-hv;
return source;
}
/** Heat source solid****************/
DEFINE_SOURCE(SRCE_solid_heat,cell,thread,dS,eqn)
{
real hv,Ts,T,source;
hv=HTC_solid_gas(cell,thread);
Ts=C_UDSI(cell,thread,SOLID_TEMP);
T=C_T(cell,thread);
source=-hv*(Ts-T);
dS[eqn]=-hv;
return source;
}
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