Learning Forum

[DexterQiu]

Hi,

I'm new to Fluent. I'm using ANSYS 2021 R2 Fluent to simulate a moving wall within a fluid domain using a UDF. When I preview the remeshed region in the next time step, I always receive an error message saying BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES. 

In some rare cases, this problem can be solved by meshing with a different mesh density. However, it will lead to a negative volume error, and it is hard to tell which part in the mesh went wrong. The refined initial mesh can make the error happens more frequently.

What could be the potential causes of the BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES error? 

Is there any way to avoid this type of error?

The error message is shown as follows.

===================================================================================

= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES

= RANK 0 PID 17876 RUNNING AT DQ-A

= EXIT STATUS: -1 (ffffffff)

===================================================================================

===================================================================================

= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES

= RANK 1 PID 45524 RUNNING AT DQ-A

= EXIT STATUS: -1 (ffffffff)

===================================================================================

The same error happens at every thread.

The dynamic mesh setting is shown as below:

blob:https://forum.ansys.com/87f07059-f185-457e-a80f-5c4121a379c5

blob:https://forum.ansys.com/8c9e94bf-207e-4dba-9509-30dcc18df694 blob:https://forum.ansys.com/ff34f16f-465f-40b9-a16e-e3a828b42658

Thank you,

Dong Qiu

[Karthik R]

Hello This might be because of the UDF or how you set up your dynamic meshing. You need to provide us with additional details so we are able to understand the issue better.
What is the UDF doing? Please also share screenshots of your starting mesh. What is this mesh quality at the beginning? Also, how did you set up your dynamic meshing?
Karthik

[DexterQiu]

Hi Karthik Thank you so much. I checked my UDF and noticed there was an incorrect parameter in my code. I have revised the code and it is working now.
Thank you Dong Qiu

[Karthik R]

Excellent! Glad it worked.
Karthik

[pratheeba.chandanagarajan]

Hi
I have the same problem.

My UDF is below:

begin_f_loop(f, thread)
{
if (t < 20.0)
{
F_PROFILE(f, thread, position) = 11.8325;
}
else if (t < 50.0)
{
F_PROFILE(f, thread, position) = 22.0135;
}

}
end_f_loop(f, thread)
}

/**********************************************************************
unsteady.c
UDF for specifying a transient temperature profile boundary condition
***********************************************************************/

DEFINE_PROFILE(unsteady_temperature, thread, position)
{
face_t f;
real t = CURRENT_TIME;

begin_f_loop(f, thread)
{
if (t < 20.0)
{
F_PROFILE(f, thread, position) = 373.15;
}
else if (t < 50.0)
{
F_PROFILE(f, thread, position) = 366.15;
}

}
end_f_loop(f, thread)
}
/**********************************************************************
unsteady.c
UDF for specifying a h-value based on time
***********************************************************************/

DEFINE_PROFILE(htc, thread, position)
{
face_t f;
real time = CURRENT_TIME;

begin_f_loop(f, thread)
{
if (time < 20.0)
{
F_PROFILE(f, thread, position) = 50.0;
}
else
{
F_PROFILE(f, thread, position) = 100.0;
}
}
end_f_loop(f, thread)
}

Below is the message displayed on FLUENT
The fl process could not be started.

===================================================================================
= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
= RANK 0 PID 8148 RUNNING AT C19FTAI
= EXIT STATUS: -1 (ffffffff)
===================================================================================

===================================================================================
= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
= RANK 1 PID 22144 RUNNING AT C19FTAI
= EXIT STATUS: -1 (ffffffff)
===================================================================================

===================================================================================
= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
= RANK 2 PID 12564 RUNNING AT C19FTAI
= EXIT STATUS: -1 (ffffffff)
===================================================================================

===================================================================================
= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
= RANK 3 PID 26620 RUNNING AT C19FTAI
= EXIT STATUS: -1 (ffffffff)

The same simulation was running few days back. i did not change any parameter.

Can you please help, ?

Thank You
Pratheeba

[pratheeba.chandanagarajan]

Just to add details I am running a transient simulation, flow through a pipe and a porous media section. There is change in velocity and temperature as a step change. I am using the viscous resistance for the porous media model and shell conduction with three layers for heat loss through a heat transfer coeffient.

Thank You
Pratheeba

[Rob]

Have a look at the DEFINE_PROFILE example in the manual - you're missing some fairly important bits at the top. I'd also review the IF statements, as 20 is less than 50 the latter value will always be used until time exceeds 50s in which case I have no idea what will happen.

[pratheeba.chandanagarajan]

Hi Rob
Thank You.

Sorry! The first header file etc was not pasted while I copied.

/**********************************************************************
unsteady.c
UDF for specifying a transient velocity profile boundary condition
***********************************************************************/

#include "udf.h"


DEFINE_PROFILE(unsteady_velocity, thread, position)
{
face_t f;
real t = CURRENT_TIME;

begin_f_loop(f, thread)
{
if (t < 20.0)
{
F_PROFILE(f, thread, position) = 11.8325;
}
else if (t < 50.0)
{
F_PROFILE(f, thread, position) = 22.0135;
}

}
end_f_loop(f, thread)
}

/**********************************************************************
unsteady.c
UDF for specifying a transient temperature profile boundary condition
***********************************************************************/

DEFINE_PROFILE(unsteady_temperature, thread, position)
{
face_t f;
real t = CURRENT_TIME;

begin_f_loop(f, thread)
{
if (t < 20.0)
{
F_PROFILE(f, thread, position) = 373.15;
}
else if (t < 50.0)
{
F_PROFILE(f, thread, position) = 366.15;
}

}
end_f_loop(f, thread)
}
/**********************************************************************
unsteady.c
UDF for specifying a h-value based on time
***********************************************************************/

DEFINE_PROFILE(htc, thread, position)
{
face_t f;
real time = CURRENT_TIME;

begin_f_loop(f, thread)
{
if (time < 20.0)
{
F_PROFILE(f, thread, position) = 50.0;
}
else
{
F_PROFILE(f, thread, position) = 100.0;
}
}
end_f_loop(f, thread)
}
This is my full UDF. Thank you for your suggestion about the IF statement. I will rewrite the IF.
Thank You
Pratheeba