[chchong001]

hello,I am trying to stop calculation automatically according to a parameter value，such as temperature,if the temperature reach 300k,stop calculation.
Can someone help me? thanks a lot!

[AlexanderZ]

Hello.

You can do it through scheme script + UDF, or fluent GUI + UDF.
I will share with you these approaches, however, text is translated by google, I'm lazy to modify, excuse me.
1. http://www.eureka.im/996.html

2.

It is a way to take advantage of ANSYS Fluent's Convergence Conditions feature.

I have implemented the content as an example.

This is an example of configuring a certain number of Iteration as a convergence condition and stopping the calculation if satisfied.

It consists of two steps.

The first step is to set the convergence criterion through the UDF.

#include "udf.h"

real stop_coeff;




DEFINE_ADJUST(stop_value, d)

{

  Thread *t;

  cell_t c;




        if(N_ITER >= 416)

        {

        real stop_coeff=1;

        }

        else

        {

        stop_coeff+=1;

        }




  thread_loop_c(t,d)

  {

    begin_c_loop(c,t)

    {

      C_UDMI(c,t,0) = stop_coeff;

    }

    end_c_loop(c,t)

  }

}

As you can see, the variable stop_coeff continues to be changed until 415 iterations, and this value is stored in the UDM.

And when it reaches 416 times of iteration which is the target that is desired, stop_coeff is saved in UDM with a certain value.

This value remains constant for the 417th iteration.

(If you are familiar with Scheme, you can do this with Scheme instead of UDF.)

The next step is to set convergence judgment based on the content of the corresponding variable (UDM).

ANSYS FLUENT's "Convergence Conditions" feature allows you to configure.

This example averages the UDMI values of the entire cell and uses the values as a convergence criterion.

Therefore, we define an average value in "Report Definitions",

And in "Convergence Conditions" we set it to judge convergence based on this value.

The results show that although the Max Iteration number has not been reached and the "Residual Convergence Criterion" is set to "none"

As a result, you can see that the calculation stops at the desired target (Iteration 417).

Obviously the content is not efficient because it loops all cells.

Nevertheless, if you apply this method appropriately, it will be enough for the setting that you desire.

Best regards

[chchong001]

thanks for your reply.you have provided 2methods,and I tried the second method as you said. But in "Convergence Conditions" ,I can't find " UDMI values",so how to set it ,could you give me the detail?

[AlexanderZ]

Originally Posted by chchong001

thanks for your reply.you have provided 2methods,and I tried the second method as you said. But in "Convergence Conditions" ,I can't find " UDMI values",so how to set it ,could you give me the detail?

Hello

in Fluent GUI go to "Solution" -> "Report Definitions" -> create new for User-Defined variable ( in Field variable choose User-Defined Memory... and select UDMI - 0, for this example)

Than you will have this report definition in "Convergence conditions" menu.

If you are not familiar with UDF and user-defined memory, try to use google and ANSYS Fluent Customization Manual

Best regards

[chchong001]

Originally Posted by AlexanderZ

Hello

in Fluent GUI go to "Solution" -> "Report Definitions" -> create new for User-Defined variable ( in Field variable choose User-Defined Memory... and select UDMI - 0, for this example)

Than you will have this report definition in "Convergence conditions" menu.

If you are not familiar with UDF and user-defined memory, try to use google and ANSYS Fluent Customization Manual

Best regards

Thanks you very much, I have already solved the problem with your help!best wishes for you!

[Saman95]

hi dear

I use Ansys fluent 2017, but i can't find "convergence conditions"
can u help me?

Also I can't find User-Defined variable in Field variable of report definitions

[AlexanderZ]

"convergence conditions" is implemented in version 18.0

best regards

[Saman95]

Originally Posted by AlexanderZ

"convergence conditions" is implemented in version 18.0

best regards

I have another question

when i go to "Report Definitions" , I have some choices like area weighted average and etc
which of these task I must choose for your example?

also what is stop criterion in convergence manager in fluent 17?

[AlexanderZ]

because you apply same value to UDMI_0 ,that's why it doesn't matter, which option you will select, area-weight average for instance.

for v17.0 I recommend you to use 1st approach with scheme script

best regards

[ksgr]

Originally Posted by AlexanderZ

Hello.

You can do it through scheme script + UDF, or fluent GUI + UDF.
I will share with you these approaches, however, text is translated by google, I'm lazy to modify, excuse me.
1. http://www.eureka.im/996.html

2.

It is a way to take advantage of ANSYS Fluent's Convergence Conditions feature.

I have implemented the content as an example.

This is an example of configuring a certain number of Iteration as a convergence condition and stopping the calculation if satisfied.

It consists of two steps.

The first step is to set the convergence criterion through the UDF.

#include "udf.h"

real stop_coeff;




DEFINE_ADJUST(stop_value, d)

{

  Thread *t;

  cell_t c;




        if(N_ITER >= 416)

        {

        real stop_coeff=1;

        }

        else

        {

        stop_coeff+=1;

        }




  thread_loop_c(t,d)

  {

    begin_c_loop(c,t)

    {

      C_UDMI(c,t,0) = stop_coeff;

    }

    end_c_loop(c,t)

  }

}

As you can see, the variable stop_coeff continues to be changed until 415 iterations, and this value is stored in the UDM.

And when it reaches 416 times of iteration which is the target that is desired, stop_coeff is saved in UDM with a certain value.

This value remains constant for the 417th iteration.

(If you are familiar with Scheme, you can do this with Scheme instead of UDF.)

The next step is to set convergence judgment based on the content of the corresponding variable (UDM).

ANSYS FLUENT's "Convergence Conditions" feature allows you to configure.

This example averages the UDMI values of the entire cell and uses the values as a convergence criterion.

Therefore, we define an average value in "Report Definitions",

And in "Convergence Conditions" we set it to judge convergence based on this value.

The results show that although the Max Iteration number has not been reached and the "Residual Convergence Criterion" is set to "none"

As a result, you can see that the calculation stops at the desired target (Iteration 417).

Obviously the content is not efficient because it loops all cells.

Nevertheless, if you apply this method appropriately, it will be enough for the setting that you desire.

Best regards

I am trying to stop simulation when the temperature of the cell zone falls below a certain threshold value. I am trying to use the second approach which is is mentioned above. However, I am not sure what should I write for the volume averaged temperature variable in place of N_ITER (which corresponds to number of iterations). Any help would be appreciated.

Thanks

[AlexanderZ]

instead of condition in UDF

if(N_ITER >= 416)

you may put here any other condition according to your needs

[Temimy]

Originally Posted by AlexanderZ

instead of condition in UDF

if(N_ITER >= 416)

you may put here any other condition according to your needs

Hello dear,
I'm using ANSYS 2019 , and try to use solution>calculation activities>Execute Commands to stop the transient solution iterations based on defined Report Definition for heat flux<100.

Can you help me to put the appropriate statement into execute command window, please.

Regards.