[mil68]

hi all, im working on a 3D transient project with UDF and imgetting this error,
Divergence detected in AMG solver: temperature
and with some changes in afew time steps i get my continuty divergent
may its bcoz of my UDF?
why is that?

[Sun]

Usually "Divergent dete..." error occurs due to the coarse or highly skewed mesh as well as large time step. You can check these two first and then post your UDF here to see if something is wrong with that.
cheers!

[mil68]

tnx buddy

[rishitosh]

hello,
I m working on a 2D conduction problem with UDF and i m getting same error,
"Divergence detected in AMG solver: temperature"
just bcoz of my UDF!!
why is that?

Dis is my udf being used for boundary condition:

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

#define pie 3.14 /*pie value*/
#define Ttran 560 /*trasitional temperature*/
#define e 2.71828 /*value of e*/
#define A 0.70 /*absorptivity*/
#define P 600 /*peak power of laser*/

DEFINE_PROFILE(ht_flx_tp_srf, t, i)
{
real x[ND_ND];
real I, T, qc, hc;
real em = 0.4;
real Tamb = 300;
real r = 200e-6;
face_t f;
begin_f_loop(f, t)
{
F_CENTROID(x, f, t);
I = A*(P / (2 * pie*pow(r, 2)))*pow(e, -(pow(x[0], 2) / (2 * pow(r, 2)))); /*due to this line I m getting dis error*/
T = F_T(f, t);
hc = (24.1e-4)*em*pow(T, 1.61);
qc = hc*(T - Tamb);
F_PROFILE(f, t, i) = I-qc;
}
end_f_loop(f, t)
}



plz take me out of this prblm...

Thank you..

with reegards.

[Sun]

I am not sure and but worth a shot...rename the "e" to something else or simply use the value itself instead of an argument.

[upeksa]

Use monitors to check the values of your profile. In that of cases, there are not any errors in the code itself, but it passes unrealistic values to the solver of Fluent, which may take into a divergence of the solution.
In your example, imagine that you are giving to your case a wall heat flux of 10^20 W/m2. That will lead into an error for sure.
Check the values and use monitors or messages in the TUI.
And use M_PI instead of #define pie 3.14: it is poor programming.
Cheers