[rezvani]

Hi everyone!
I'm trying to simulate incompressible material flow in friction welding. im use udf for viscosity and heat transfer in pin surface.
Boundary conditions: velocity inlet, pressure outlet, slip condition walls. heat input by udf on copled via system method in surface of pin.
energy equation is on. pressure base solver used in steady state.
After 3 iterations, Divergence detected in AMG solver: pressure coupled Stabilizing temperature to enhance linear solver robustness.
temperature limited to 1.000000e+00 in 1695 cells on zone 4 in domain 1
temperature limited to 5.000000e+03 in 3961 cells on zone 4 in domain 1
Divergence detected in AMG solver: pressure coupled
Error at host: floati

iter continuity x-velocity y-velocity z-velocity energy time/iter
temperature limited to 2.500000e+02 in 2034 cells on zone 4 in domain 1
temperature limited to 8.000000e+03 in 2 cells on zone 4 in domain 1
1 1.0000e+00 2.5067e-03 3.3226e-03 6.4718e-03 3.3263e-03 0:04:18 19
Stabilizing pressure coupled to enhance linear solver robustness.
temperature limited to 2.500000e+02 in 111 cells on zone 4 in domain 1
temperature limited to 8.000000e+03 in 81 cells on zone 4 in domain 1
2 1.0000e+00 1.1354e-03 1.5119e-03 2.2842e-03 5.9263e-03 0:06:37 18
Stabilizing pressure coupled to enhance linear solver robustness.
Stabilizing pressure coupled using GMRES to enhance linear solver robustness.

Experiencing convergence difficulties - temporarily relaxing and trying again...

Experiencing convergence difficulties - temporarily relaxing and trying again...

Experiencing convergence difficulties - temporarily relaxing and trying again...

Experiencing convergence difficulties - temporarily relaxing and trying again...
Stabilizing pressure coupled to enhance linear solver robustness.
temperature limited to 2.500000e+02 in 3164 cells on zone 4 in domain 1
temperature limited to 8.000000e+03 in 583 cells on zone 4 in domain 1
3 1.0000e+00 8.4188e-03 3.7937e-03 1.3550e-02 5.5499e+00 0:14:58 17

E
Error at Node 1: floating point excreptionror at Node 0:
floating point exception
Stabilizing pressure coupled to enhance linear solver robustness.
Stabilizing pressure coupled using GMRES to enhance linear solver robustness.

Experiencing convergence difficulties - temporarily relaxing and trying again...

Experiencing convergence difficulties - temporarily relaxing and trying again...

Experiencing convergence difficulties - temporarily relaxing and trying again...

Experiencing convergence difficulties - temporarily relaxing and trying again...
Stabilizing pressure coupled to enhance linear solver robustness.
Stabilizing pressure coupled using GMRES to enhance linear solver robustness.

Experiencing convergence difficulties - temporarily relaxing and trying again...

Divergence detected in AMG solver: pressure coupled Stabilizing temperature to enhance linear solver robustness.
temperature limited to 2.500000e+02 in 900 cells on zone 4 in domain 1
temperature limited to 8.000000e+03 in 2187 cells on zone 4 in domain 1
Divergence detected in AMG solver: pressure coupled
Error at host: floating point exception

thank you.
Best Regards.

[AlexanderZ]

there is no way to help you based on information you've provided

show your UDF if you think problem comes from it
change variables inside UDF to constant values and try to run case again.

if it doesn't work, it means, problem is in your settings not in UDF

[pakk]

Initialize, don't run, plot the viscosity. Is it what you expected?

[rezvani]

Originally Posted by pakk

Initialize, don't run, plot the viscosity. Is it what you expected?

initial viscosity is 7*e8 and strane rate 0.
divergence may be produced by heat generation udf. temperature (heat flux) dont travel into flow

#include "udf.h"
real x[ND_ND], A[ND_ND], c[ND_ND], rcal[ND_ND], Atotal[ND_ND];
/* this will hold the position vector */
face_t f;
real r, q, qt, y;
DEFINE_PROFILE(heatfx,t,i)
{
int abst;
Atotal[0]=0;
Atotal[1]= 0;
Atotal[2]=0;
c[0]=0;
c[1]= 0;
c[2]=0.006;
qt=0;
begin_f_loop(f,t)
{
F_CENTROID(x,f,t);
NV_VV(rcal,=,x,-,c);
r=NV_MAG(rcal);
if(r<0.0059&&r>0)
{
q=(3*2272*r)/(2*3.14*(pow(0.0059,3))); /*//w/m2*/
F_PROFILE(f,t,i)=q;
F_AREA(A,f,t);
qt=qt+q*NV_MAG(A);
/*printf("qAreas=%f%f%f%f\n",q,A[0],A[1],A[2]); */
NV_VV(Atotal,=,Atotal,+,A);
}
else
{
F_PROFILE(f,t,i)=-30*(F_T(f,t)-298);/*//w/m2*/
y=F_T(f,t);
}
}
end_f_loop(f,t)
/*printf("\nQtdiff=%f\n",qt); */
}

[pakk]

Originally Posted by rezvani

initial viscosity is 7*e8 and strane rate 0.
divergence may be produced by heat generation udf. temperature (heat flux) dont travel into flow

#include "udf.h"
real x[ND_ND], A[ND_ND], c[ND_ND], rcal[ND_ND], Atotal[ND_ND];
/* this will hold the position vector */
face_t f;
real r, q, qt, y;
DEFINE_PROFILE(heatfx,t,i)
{
int abst;
Atotal[0]=0;
Atotal[1]= 0;
Atotal[2]=0;
c[0]=0;
c[1]= 0;
c[2]=0.006;
qt=0;
begin_f_loop(f,t)
{
F_CENTROID(x,f,t);
NV_VV(rcal,=,x,-,c);
r=NV_MAG(rcal);
if(r<0.0059&&r>0)
{
q=(3*2272*r)/(2*3.14*(pow(0.0059,3))); /*//w/m2*/
F_PROFILE(f,t,i)=q;
F_AREA(A,f,t);
qt=qt+q*NV_MAG(A);
/*printf("qAreas=%f%f%f%f\n",q,A[0],A[1],A[2]); */
NV_VV(Atotal,=,Atotal,+,A);
}
else
{
F_PROFILE(f,t,i)=-30*(F_T(f,t)-298);/*//w/m2*/
y=F_T(f,t);
}
}
end_f_loop(f,t)
/*printf("\nQtdiff=%f\n",qt); */
}

Is that viscosity really what you want? A million times higher than peanut butter?

[rezvani]

Originally Posted by pakk

Is that viscosity really what you want? A million times higher than peanut butter?

this is viscosity of solid metal in 350 k . i try chose higer temperature like 800k for smaller viscosity.

[AlexanderZ]

your code seems to be correct.
you may try to check values, which you apply.
you may try to simplify your case for testing, until you will get what you expect
you may try to use UDMs to store and plot your source and material properties