[le.martinez]

Hi everyone!
I 've working with a udf to simulate the viscosity of alumiunium in function of temperarture and strain rate. Neverthless, the macros C_STRAIN_RATE_MAG(c, t) its not working. When I write the macros fluent show a divergence problems. (I atached the udf)
#include "udf.h"
#include "mem.h"
#define Q 176867 //J/mol
#define A 4.46e+13
#define n 5.86
#define R 8.314 //J/molK
#define alpha 0.0118
DEFINE_PROPERTY(cell_viscosity, c, t)
{
real temp = C_T(c, t);
real mu_lam;
real Z;
real Flow_stress;
real x;
real strain;
if (strain < 0)
{
strain = 10;
}
else
{
strain = C_STRAIN_RATE_MAG(c, t);
}
Z = pow((strain), (Q / (R*temp)));
x = pow((Z / A), (1. / n));
Flow_stress = (1. / alpha)*(log(x + sqrt(pow(x, 2) + 1.)));
mu_lam = Flow_stress / (3.*strain);
if (mu_lam > 0)
return mu_lam;
}
But when I use a constante value of strain rate, the udf works perfect and match whith my had writing calculus ( I atached the another udf)
#include "udf.h"
#include "mem.h"
#define Q 176867 //J/mol
#define A 4.46e+13
#define n 5.86
#define R 8.314 //J/molK
#define alpha 0.0118
DEFINE_PROPERTY(cell_viscosity, c, t)
{
real temp = C_T(c, t);
real mu_lam;
real Z;
real Flow_stress;
real x;
real strain = 10;
Z = pow((strain), (Q / (R*temp)));
x = pow((Z / A), (1. / n));
Flow_stress = (1. / alpha)*(log(x + sqrt(pow(x, 2) + 1.)));
mu_lam = Flow_stress / (3.*strain);
if (mu_lam > 0)
return mu_lam;
}
I hope someone could help me, thanks by advanced.

[elkeju]

Hi,

Did you already solved your problem? I'm stucked with the same issue and i do not really know how to implement a if condition for t=0.

Thanks in advance!