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September 5, 2012, 21:07 |
Why simulation results showing "nan" values?
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#1 |
Member
Sangeeta
Join Date: Jul 2012
Location: Kingston, Canada
Posts: 70
Rep Power: 14 |
Hello everyone,
I am running solidDisplacementFoam for 3D model. After simulation log file is showing "nan" values as given below: Iteration: 98 GAMG: Solving for T, Initial residual = 3.24013e-09, Final residual = 3.24013e-09, No Iterations 0 Min/Max/Ave T:-99.9999 99.9998 4.79039 GAMG: Solving for Dx, Initial residual = nan, Final residual = nan, No Iterations 1000 GAMG: Solving for Dy, Initial residual = nan, Final residual = nan, No Iterations 1000 GAMG: Solving for Dz, Initial residual = nan, Final residual = nan, No Iterations 1000 Min/Max/Ave DEqnnan nan nan) (nan nan nan) (nan nan nan) ExecutionTime = 19286.7 s ClockTime = 19301 s Iteration: 99 GAMG: Solving for T, Initial residual = 3.24013e-09, Final residual = 3.24013e-09, No Iterations 0 Min/Max/Ave T:-99.9999 99.9998 4.79039 GAMG: Solving for Dx, Initial residual = nan, Final residual = nan, No Iterations 1000 GAMG: Solving for Dy, Initial residual = nan, Final residual = nan, No Iterations 1000 GAMG: Solving for Dz, Initial residual = nan, Final residual = nan, No Iterations 1000 Min/Max/Ave DEqnnan nan nan) (nan nan nan) (nan nan nan) ExecutionTime = 19321.6 s ClockTime = 19336 s Iteration: 100 GAMG: Solving for T, Initial residual = 3.24013e-09, Final residual = 3.24013e-09, No Iterations 0 Min/Max/Ave T:-99.9999 99.9998 4.79039 GAMG: Solving for Dx, Initial residual = nan, Final residual = nan, No Iterations 1000 GAMG: Solving for Dy, Initial residual = nan, Final residual = nan, No Iterations 1000 GAMG: Solving for Dz, Initial residual = nan, Final residual = nan, No Iterations 1000 Min/Max/Ave DEqnnan nan nan) (nan nan nan) (nan nan nan) Max sigmaEq = nan ExecutionTime = 19357.5 s ClockTime = 19372 s Does anyone have any idea why this problem is coming? Thanks, Sangeeta |
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September 6, 2012, 14:45 |
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#2 |
Retired Super Moderator
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 10,980
Blog Entries: 45
Rep Power: 128 |
Greetings Sangeeta,
That basically means that the solver started to diverge when trying to solve Dx, Dy and Dz. You should look higher in the log file and look for where the simulation starts diverging. It can happen due to several reasons:
About keeping a log: taking as an example the tutorial "stressAnalysis/solidDisplacementFoam/plateHole", you can easily run that tutorial and clean that case by running the following commands:
Bruno
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September 6, 2012, 22:06 |
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#3 | |
Member
Sangeeta
Join Date: Jul 2012
Location: Kingston, Canada
Posts: 70
Rep Power: 14 |
Quote:
Hi Bruno, Thank you for the reply. I have generated a 3D mesh in snappyHexMesh and using this mesh for solving stress analysis by using solidDisplacementFoam solver. I have re-checked my boundary conditions, and fvSchemes (relaxation value etc.). I have used tighter tolerance and increased number of ncorrectors but still I am having same problem. I have gotten good simulation results for similar problem for 2D. Do you think that this problem is coming because of 3D geometry? Thanks in advance. Regards, Sangeeta |
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September 8, 2012, 14:21 |
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#4 |
Retired Super Moderator
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
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Hi Sangeeta,
OK, there are two other points you can check/test:
Bruno
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September 10, 2012, 12:37 |
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#5 | |
Member
Sangeeta
Join Date: Jul 2012
Location: Kingston, Canada
Posts: 70
Rep Power: 14 |
Quote:
Thanks a lot for the reply. I hope this will help to solve my problem. Regards, Sangeeta |
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