Steady State Heat Transfer Problem

Anonymous · ‎07-03-2012

I am using Simulation Mechanical 2012.

I have a beam and I have applied a temperature to each end of the beam to look at temperature distribution along the beam.

Under certain conditions, my results will show temperatures far outside the range of my 2 initial applied temperatures. My initial temperatures are 90F and 110F and my results can show between -130F and 190F.

It gets into this mode when I increase my total number of elements by either changing the size of my mesh or increasing the length of my beam. As best that I can tell, I have this problem above 100,000 elements.

Help would be appreciated.

Anonymous · ‎07-03-2012

There was a similar problem fixed in an incoming service pack. Can you post your model to check?

Anonymous · ‎07-05-2012

Has the service pack already been released?

I cannot upload a file that big so I have attached a few screenshots.

Is there another method to post the fem file?

Summary Log:

Autodesk (R) Simulation Steady-State Heat Transfer
Version 2012.01.00.0017-W64/X64 15-Jun-2011
Copyright (c) 2011, Autodesk, Inc. All rights reserved.

      DATE: JULY 5, 2012                  
      TIME: 09:06 AM
      Input Model: H:\FEA\Plain Beam\Rod.ds_data\1\ds


           PROGRAM VERSION: 201201000017
           ALG.DLL VERSION: 201201000017
     AlgConfig.DLL VERSION: 201201000017
      Agsdb_AR.DLL VERSION: 201201000017
      AMGSolve.DLL VERSION: 201201000017
      AlgSolve.DLL VERSION: 201201000017
 

 **** Model Unit System Settings:
      --------------------------------------------
       Unit System              : English (in)
       Force                    : lbf
       Length                   : in
       Time                     : s
       Temperature (Absolute)   : deg F (R)
       Thermal Energy           : in*lbf
       Voltage                  : V
       Current                  : A
       Electrical Resistance    : ohm
       Mass                     : lbf*s^2/in
      --------------------------------------------

 
 Thermal
                                                  
 **** CONTROL INFORMATION                         
                                                  
      number of node points                    =    182701
      number of element types                  =    2
      analysis type code                       =    10
      equations per block                      =    0
      bandwidth minimization flag              =    0

 **** PHYSICAL CONSTANTS USED WHEN APPLICABLE 

      The Stefan-Boltzmann Constant      =  3.083E-11
      Temperature Increment to Absolute  =  4.597E+02
                                                  
 **** NON-LINEAR ITERATION CONTROL PARAMETERS     
 
      Nonlinear control option           =          OFF
      Convergence criterion              =          2
      Maximum number of iterations       =          15
      Interval for monitoring            =          5
      Corrective tolerance               =          1.0000E-03
      Relative tolerance                 =          1.0000E-03
      Relaxation parameter               =          1.0000E+00
 
 **** PRINT OF NODAL DATA SUPPRESSED              
 
 **** PRINT OF EQUATION NUMBERS SUPPRESSED        

 **** FLUID FLOW CONVECTION IS NOT INCLUDED IN THIS MODEL.

 **** HARD DISK FILE SIZE INFORMATION FOR PROCESSOR:

      Available hard disk space on H drive =  38276.797 megabytes

                                                  
 **** LOAD CASE MULTIPLIERS                       
                                                  
      Boundary temperature multiplier       1.000
      Convection multiplier                 1.000
      Radiation multiplier                  1.000
      Heat generation multiplier            1.000

 **** AMG SOLVER CONTROL INFORMATION 

      Convergence Tolerance    =   1.000E-06
      Maximum Iteration Number =     1000
      AMG log output level     =       -1
 
 **** Invoking Iterative AMG Solver ...
 **** End solution 
 
 
                                                  
 **** TEMPORARY FILE STORAGE (MEGABYTES)          
      ----------------------------------          
       UNIT NO.  7 :      1.394
       UNIT NO.  8 :      7.710
       UNIT NO.  9 :      0.040
       UNIT NO. 10 :      0.040
       UNIT NO. 11 :    265.467
       UNIT NO. 12 :      0.000
       UNIT NO. 13 :      0.040
       UNIT NO. 14 :      0.000
       UNIT NO. 15 :      0.040
       UNIT NO. 18 :      0.040
       UNIT NO. 65 :      1.394
       UNIT NO. 67 :     85.904

       TOTAL       :     362.070



 **** End of File ****

John_Holtz · ‎07-05-2012

Hi,

My guess is that you can get accurate results by reducing the "Stiffness" of the Controlled Temperatures. According to the documentation, the stiffness should be "(2-3 orders of magnitude higher than the conductivity of the materials in your model)".

John Holtz, P.E.
Global Product Support
Autodesk, Inc.

If not provided, indicate the version of Inventor Nastran you are using.
If the issue is related to a model, attach the model! See What files to provide when the model is needed.

Anonymous · ‎07-05-2012

Thank you very much. That seems to have fixed the issue.

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