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Old   March 23, 2004, 12:53
Default UDF Problem
  #1
Big Stone
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I run a case using UDF compiled by C++. every thing is OK. after I save the case and data, I can not reopen it . It appears some error information below: if anyone know this, please help me.

Error: FLUENT received fatal signal (ACCESS_VIOLATION) 1. Note exact events leading to error. 2. Save case/data under new name. 3. Exit program and restart to continue. 4. Report error to your distributor. Error Object: ()
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Old   March 24, 2004, 04:51
Default Re: UDF Problem
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Ale
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Hi,

I suggest you to search for "access violation" in this site; the error is quite common and has been discussed quite a lot.

However, I think that the error is connected to the access to memory locations by Fluent. I had the same problems you have, and in my case It was connected to the usage of UDS gradients, which are usually not defined at the beginning of the calculation (even if you start from a previous calculation).

The simplest way to solve the problem is to use gradients only if they are defined. For example, if you are using gradients of UDS i, you can set this control:

if (NULL != THREAD_STORAGE(t,SV_UDSI_G(i))) { ...do what you have to do... } else { ...write alternative instructions that do not need gradients... }

Of course, the 'else' condition will occur only at the first iteration.

I hope this helps.

Ale
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Old   March 24, 2004, 11:44
Default Re: UDF Problem
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Big Stone
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HI, Ale

Thank you very much. I will try to figure it out.
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Old   March 24, 2004, 11:52
Default Re: UDF Problem
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Big Stone
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Hi, Ale

Actually it is a case from the tutorial of FLUENT. Is it possible for it to have this problem.If you want , I can send the code to you and see what's going on?
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Old   March 25, 2004, 06:02
Default Re: UDF Problem
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Ale
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Hi,

Which is the tutorial? If you like, post your code.

Regards,

Ale
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Old   March 25, 2004, 09:33
Default Re: UDF Problem
  #6
Aleex
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Thank you for your answer! I temporary solve this problem. I manually storage pressure values from previous time step in static array (static double prevP[MAX_VALUES_COUNT]) and hook to DEFINE_EXECUTE_AT_END and DEFINE_INIT. It`s work!

Regards, Aleex.
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Old   March 25, 2004, 09:37
Default Sorry. It`s for FJ :)
  #7
Aleex
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Old   March 25, 2004, 10:32
Default Re: UDF Problem
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Big Stone
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Ale Thanks

It is the tutorial of bubble break in a column. If you do not have it , I will send you email box.
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