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how to upload mutiple UDFs in FLUENT.

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Old   March 1, 2005, 02:30
Default how to upload mutiple UDFs in FLUENT.
  #1
shunahshep
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Hi All,

I am trying to simulate a situation that requires me to use 2 UDFs - one for the inlet velocity and the other for a temperature dependent viscosity. As a test case, i just tried to run the 2 UDFs available in the FLUENT UDF manual simultaneously. I created a simple rectangular mesh and exactly cutpasted the program for the udf called inlet_x_velocity into a new file in C++ (called inlet_x_velocity). Then i cutpasted the program for temperature-dependent viscosity given in the UDF manual into a different file (called cell_viscosity):

When i go to Define->User defined->Functions->Interpreted and carry out the instructions outlined in the UDF manual, i can upload each function separately without any problem. however, only the function that i upload last stays into the memory for later use. Can someone please tell me how to upload multiple UDFs in FLUENT?

Thanks very much in anticipation. Regards, Shunahshep.
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Old   March 1, 2005, 02:57
Default Re: how to upload mutiple UDFs in FLUENT.
  #2
mateus
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Hi!

Just write them one after another in one file and interpete it.

by MATEUS
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Old   March 1, 2005, 04:08
Default Re: how to upload mutiple UDFs in FLUENT.
  #3
Frank Meißen
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Hi,

in Fluent 6.1.x you have to define all functions in one file. AFAIK in Fluent 6.2.x you can load multiple files.

Frank
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Old   March 1, 2005, 15:31
Default Re: how to upload mutiple UDFs in FLUENT.
  #4
shunahshep
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Hi Mateus,

Thanks very much for your suggestion. I tried cutpasting both functions into the same file and then running the simulation, but got the following error when i tried to interpret my UDF:

Error: udfconfig.h: line 22: parse error.

Can you please tell me how to overcome the error.

Frank, thanks for your post. But unfortunately i only have Fluent Version 6.1.22.

Regards, Shunahshep.
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Old   March 1, 2005, 15:58
Default Problem with initializing a case file with 2 UDFs.
  #5
shunahshep
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Hi,

I could eliminate the parse error by deleting the udf.h file header in the second function. The UDF is interpreted successfully now. But during the solution initialization step, i get the following error:

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: ()

I have no idea what it means. Can someone please help me?

Thanks,

Shunahshep.
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Old   March 2, 2005, 04:38
Default Re: Problem with initializing a case file with 2 U
  #6
mateus
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Hi!

I think that has nothing to do with interpreting 2 udfs. There is something very vrong with your problem. Maybe there's an error in one of the udfs - try to start the simulation with just one at the time. Maybe the 2 udfs can't work together (but I doubt that thats the problem)...

good luck MATEUS
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Old   March 2, 2005, 11:05
Default Re: Problem with initializing a case file with 2 U
  #7
major
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hello,Shunahshep, I have been the same problem as you. You should exit your fluent case and restart fluent. It can work again. good luck! I have a question for your help. I have writen a program as following: #include "udf.h" DEFINE_PROPERTY(cell_diffusion_coefficent,c,t) { real ud; real rho=C_R(c,t); real mu=C_MU_EFF(c,t); ud=mu/rho; return ud; } When I interpreted it into fluent. I get the following error message:line 1arse error I don't know the reason. Would you like to help me? Thank you very much! major
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Old   March 2, 2005, 18:22
Default Re: Problem with initializing a case file with 2 U
  #8
shunahshep
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Mateus and Major,

Thx for your suggestions regarding my problem. I tried reloading the case many times (restarting fluent each time) but still it gave me the same error. Mateus i can send u my UDFs if you want to take a look - they can't be wrong since they are just cut-pasted from Fluent UDF manual.

Major, about your UDF, i should say that i haven't any personal experience working with diffusion yet (actually i am only beginning to use fluent UDFs). But i think i can still point out to one thing that i came across in the udf manual which i think u shd go back to.

You should probably use a DEFINE_DIFFUSIVITY macro instead of the DEFINE_PROPERTY macro that you are currently using. (Please check the UDF manual, the DEFINE_DIFFUSIVITY macro has three arguments c,t,i instead of just c,t for DEFINE_PROPERTY macro).

If you are still having problems email me your journal file (for the case) with the BCs and Operating Conditions - i'll try to see if i can make it work.

Regards, Shunahshep.
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Old   March 2, 2005, 22:56
Default Re: Problem with initializing a case file with 2 U
  #9
major
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Shunahshep: Thank you very much! I have done it. good luck to you! major
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