CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > CONVERGE

BC in Simple Channel Flow Problem

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 11, 2016, 05:12
Default BC in Simple Channel Flow Problem
  #1
New Member
 
Afiqah Hamzah
Join Date: Jul 2016
Posts: 12
Rep Power: 6
hmzha is on a distinguished road
Hi,

I am using the converge simple channel flow tutorial and changing the inlet pressure boundary condition to impose more and more pressure gradient on the flow. However at some point, the simulation crashes when the pressure difference between inlet and outlet is more than 20 Pa.

Error that comes up is this

JOB ABORT invoked by rank 0:
ERROR: Something is wrong in function get_temp_from_table_massfrac: upper_energy_value must be greater than lower_energy_value!
upper_energy_value is -nan, and lower_energy_value is -nan.

I use the same boundary and initial condition as in the tutorial except modifying the inlet and initial pressure to 100020 Pa.

Is there something that I am doing is not correct?

Thanks
hmzha is offline   Reply With Quote

Old   July 12, 2016, 10:20
Default
  #2
New Member
 
Anshul Mittal's Avatar
 
Anshul Mittal
Join Date: Jul 2016
Location: Convergent Science, Madison WI
Posts: 2
Rep Power: 0
Anshul Mittal is on a distinguished road
Hello,

From the error message we can see that NaN was detected. This indicates that one or more of the equations did not converge and blew up.
You can look in the log file to see which equation is causing the issue. Detailed information in the log file is printed when the screen_print_level is set to 2.

What is the version number and release date of CONVERGE that you are using?

Thank you,
__________________
Anshul Mittal
Research Engineer | Applications

CONVERGECFD
Anshul Mittal is offline   Reply With Quote

Old   July 12, 2016, 20:31
Default
  #3
New Member
 
Afiqah Hamzah
Join Date: Jul 2016
Posts: 12
Rep Power: 6
hmzha is on a distinguished road
Hi Anshul,

Thanks for your reply. I am currently using v2.3 (Jan 29, 2016).

Yes the screen_print_level is already set to 2.

Which log file should I refer to? result.out?

And what causes only small pressure difference (20Pa) for the simulation to blow up? Should I change the type of solver as well?

Thanks
hmzha is offline   Reply With Quote

Old   July 13, 2016, 10:03
Default
  #4
New Member
 
Anshul Mittal's Avatar
 
Anshul Mittal
Join Date: Jul 2016
Location: Convergent Science, Madison WI
Posts: 2
Rep Power: 0
Anshul Mittal is on a distinguished road
Hello,

When you run CONVERGE from a terminal, lot of information is printed on the screen. Many times we direct the screen output to a file and this file is commonly referred to as log file.
It is possible that result.out might contain that information.
You can check Figures 22.9-22.11 in CONVERGE Manual to see how a log file looks.

Thank you,
__________________
Anshul Mittal
Research Engineer | Applications

CONVERGECFD
Anshul Mittal is offline   Reply With Quote

Old   March 1, 2017, 02:57
Default
  #5
New Member
 
Join Date: Feb 2017
Posts: 8
Rep Power: 6
melodia is on a distinguished road
Hello Anshul,

I have the same problem as Hmzha. Error that comes up is:

ERROR: Something is wrong in function get_temp_from_table_massfrac: upper_energy_value must be greater than lower_energy_value!
upper_energy_value is nan, and lower_energy_value is nan.

I have a .log where, as you told, I could see which equation blew up.

Where can I detect this error?

Thanks in advance
melodia is offline   Reply With Quote

Old   March 22, 2017, 13:22
Default
  #6
New Member
 
Join Date: Mar 2017
Posts: 7
Rep Power: 6
-nan is on a distinguished road
Quote:
Originally Posted by melodia View Post
Hello Anshul,

I have the same problem as Hmzha. Error that comes up is:

ERROR: Something is wrong in function get_temp_from_table_massfrac: upper_energy_value must be greater than lower_energy_value!
upper_energy_value is nan, and lower_energy_value is nan.

I have a .log where, as you told, I could see which equation blew up.

Where can I detect this error?

Thanks in advance
Hi, I am working on a pressure-based steady problem and am encountering this same error. Did you sort it? Or if anyone else has any suggestions.

Thanks
-nan is offline   Reply With Quote

Old   March 23, 2017, 04:54
Default
  #7
New Member
 
Join Date: Feb 2017
Posts: 8
Rep Power: 6
melodia is on a distinguished road
Hi,

In my case, the error was that the mesh was too coarse or too thin so the turbulence didn't work well.

If you have generated a .log, you could know what equation blew up.

I hope this explanation would help you!!
melodia is offline   Reply With Quote

Old   March 24, 2017, 10:54
Default
  #8
Member
 
Yaju's Avatar
 
Yajuvendra Shekhawat
Join Date: Mar 2017
Location: Convergent Science, Madison WI
Posts: 41
Rep Power: 6
Yaju is on a distinguished road
Hi,

JOB ABORT invoked by rank 0:
ERROR: Something is wrong in function get_temp_from_table_massfrac: upper_energy_value must be greater than lower_energy_value!
upper_energy_value is -nan, and lower_energy_value is -nan.

The above error generally occurs when energy goes out of bounds, i.e. there is no temperature corresponding to the internal energy that we are solving for. Please make sure that you are using the recommended settings for solving all the conservation equations, also have a look at the geometry and make sure you have appropriate number of cells for narrow regions of the geometry.

If you are still encountering this error, please send your case setup to support@convergecfd.com for further support.
__________________
Yajuvendra Shekhawat
Research Engineer - Applications Group
CONVERGECFD
Yaju is offline   Reply With Quote

Old   March 24, 2017, 14:56
Default
  #9
New Member
 
Join Date: Mar 2017
Posts: 7
Rep Power: 6
-nan is on a distinguished road
Thanks,
It seems I was able to get rid of the energy_value error by either removing a permanent fixed embedding cylinder or decreasing the base grid, but then was encountering segmentation fault. I am using default values for the conservation equations. An interesting note is that I can run the same grid/mesh settings with a transient solver. Let me know if I should start a new thread or send my .cvg to the support email.
-nan is offline   Reply With Quote

Old   December 28, 2017, 12:32
Default
  #10
New Member
 
Join Date: Dec 2017
Posts: 6
Rep Power: 5
Russell1 is on a distinguished road
Hey everyone,
could anyone figure out what problem is whenever this error appears?
ERROR: Something is wrong in function get_temp_from_table_massfrac: upper_energy_value must be greater than lower_energy_value!
upper_energy_value is nan, and lower_energy_value is nan.

Any idea what does it mean?!

Last edited by Russell1; December 28, 2017 at 18:57.
Russell1 is offline   Reply With Quote

Old   December 28, 2017, 16:41
Default
  #11
Senior Member
 
ksrivast's Avatar
 
Kislaya Srivastava
Join Date: Sep 2017
Location: Convergent Science, Northville MI
Posts: 110
Rep Power: 5
ksrivast is on a distinguished road
New thread created for the above.
__________________
Kislaya Srivastava
Research Engineer | Applications
CONVERGECFD
ksrivast is offline   Reply With Quote

Old   March 29, 2021, 13:03
Default
  #12
New Member
 
Tom Mo
Join Date: Mar 2021
Posts: 1
Rep Power: 0
Qm260 is on a distinguished road
Hey everyone,
I recently encountered the same issue by only increasing the inlet gas temperature, has anyone figure out what problem is?
WARNING: temperature extrapolation error found
FATAL ERROR: Something is wrong in function get_temp_from_table_massfrac: upper_energy_value must be greater than lower_energy_value!
upper_energy_value is nan, and lower_energy_value is nan.
Qm260 is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Problem with SIMPLEC-like finite volume channel flow boundary conditions ghobold Main CFD Forum 3 June 15, 2015 11:14
Setting boundary conditions for simple pipe flow with flow direction changing in time Sipher FLUENT 1 May 4, 2015 20:05
mesh motion problem in open channel flow teo88 FLUENT 0 April 21, 2015 04:23
Create simple open channel flow hydr_eng1805 FLOW-3D 2 October 24, 2014 07:35
[GAMBIT] Gambit & 3d open channel flow mesh problem esgee ANSYS Meshing & Geometry 7 April 10, 2012 00:51


All times are GMT -4. The time now is 04:42.