[souza.emer]

Hello all,

I'm new with Fluent and UDF.
I want to make a modification on the Ranz-Marshall Model using a base UDF given in the documentation. This modification is simply to change the constants and add a Gamma expression.
The purpose is to test if this function will help me to heat a granular phase with a gas phase entering in a domain at 2373 K (blast furnace tuyere process)
My doubt is: this UDF that I wrote is really taking the properties of the granular secondary phase (Eulerian-Eulerian)? I'm already using the UDF and fluent successfully read it.

Here are the subroutines:

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

FLUENT DOCUMENTATION Ranz-Marshall Model

#include "udf.h"
#define PR_NUMBER(cp,mu,k) ((cp)*(mu)/(k))
#define IP_HEAT_COEFF(vof,k,nu,d) ((vof)*6.*(k)*(Nu)/(d)/(d))
static real heat_ranz_marshall(cell_t c, Thread *ti, Thread *tj)
{
real h;
real d = C_PHASE_DIAMETER(c,tj);
real k = C_K_L(c,ti);
real NV_VEC(v), vel, Re, Pr, Nu;
NV_DD(v,=,C_U(c,tj),C_V(c,tj),C_W(c,tj),-,C_U(c,ti),C_V(c,ti),C_W(c,ti));
vel = NV_MAG(v);
Re = RE_NUMBER(C_R(c,ti),vel,d,C_MU_L(c,ti));
Pr = PR_NUMBER (C_CP(c,ti),C_MU_L(c,ti),k);
Nu = 2. + 0.6*sqrt(Re)*pow(Pr,1./3.);
h = IP_HEAT_COEFF(C_VOF(c,tj),k,Nu,d);
return h;
}
DEFINE_EXCHANGE_PROPERTY(heat_udf, c, t, i, j)
{
Thread *ti = THREAD_SUB_THREAD(t,i);
Thread *tj = THREAD_SUB_THREAD(t,j);
real val;
val = heat_ranz_marshall(c,ti, tj);
return val;
}

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

Ranz-Marshall Model MODIFIED

#include "udf.h"
#include "math.h"

#define PR_NUMBER(cp,mu,k) ((cp)*(mu)/(k))
#define IP_HEAT_COEFF(vof,k,nu,d) ((vof)*6.*(k)*(Nu)/(d)/(d))

static real heat_ranz_marshall(cell_t c, Thread *ti, Thread *tj) /* i -- gas phase; j -- granular-phase */
{
real gamma; /*paper shen*/
real t_sec = C_T(c, tj); /*secondary phase (coke) temperature*/
gamma = 0.2 - 0.18*MIN(1.0, MAX(0, (t_sec - 1473.) / 200.));

real h;
real d = C_PHASE_DIAMETER(c, tj); /*secondary phase (coke) diameter*/
real k = C_K_L(c, ti);
real NV_VEC(v), vel, Re, Pr, Nu;
NV_DD(v,=, C_U(c, tj), C_V(c, tj), C_W(c, tj), -, C_U(c, ti), C_V(c, ti), C_W(c, ti));
vel = NV_MAG(v);
Re = RE_NUMBER(C_R(c, ti), vel, d, C_MU_L(c, ti));
Pr = PR_NUMBER(C_CP(c, ti), C_MU_L(c, ti), k);
Nu = 2. + 0.6*pow(Pr,0.333)*pow(9.*Re,0.5);
h = IP_HEAT_COEFF(C_VOF(c, tj), k, Nu, d);
h = gamma*h;
return h;
}
DEFINE_EXCHANGE_PROPERTY(heat_udf, c, t, i, j)
{
Thread *ti = THREAD_SUB_THREAD(t, i);
Thread *tj = THREAD_SUB_THREAD(t, j);
real val;
val = heat_ranz_marshall(c, ti, tj);
return val;
}

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

Can anyone help with ANY suggestions? If need more details, just ask.
Sorry for my bad English.

PS: the formulas are attached

Paper: Three-Dimensional Modeling of Flow and Thermochemical
Behavior in a Blast Furnace (YANSONG Shen, BAOYU GUO, SHENG CHEW, PETER AUSTIN, and AIBING YU)

Results so far: I can't heat my granular phase with my gas (Figures attached)