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-   -   Error #001100279 (http://www.cfd-online.com/Forums/cfx/97588-error-001100279-a.html)

mahesh_1402 February 21, 2012 02:42

Error #001100279
 
/*this is out file error message*/

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| Floating point exception: Overflow |

+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| Stopped in routine FPX: C_FPX_HANDLER |

+--------------------------------------------------------------------+
+--------------------------------------------------------------------+
| An error has occurred in cfx5solve: |
| |
| The ANSYS CFX solver exited with return code 1. No results file |
| has been created. |
+--------------------------------------------------------------------+
End of solution stage.
+--------------------------------------------------------------------+
| The following transient and backup files written by the ANSYS CFX |
| solver have been saved in the directory E:\original |
| model\transient\solve2\with diffuser_original_trans_18feb_002: |
| |
| 1115_full.trn, 1114_full.trn, 1113_full.trn, 1112_full.trn, |
| 1111_full.trn, 1110_full.trn, 1109_full.trn, 1108_full.trn, |
| 1107_full.trn, 1106_full.trn, 1105_full.trn, 1104_full.trn, |
| 1103_full.trn |
+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| The following user files have been saved in the directory |
| E:\original model\transient\solve2\with |
| diffuser_original_trans_18feb_002: |
| |
| mon |
+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| Warning! |
| |
| After waiting for 60 seconds, 1 solver manager process(es) appear |
| not to have noticed that this run has ended. You may get errors |
| removing some files if they are still open in the solver manager. |
+--------------------------------------------------------------------+

This run of the ANSYS CFX Solver has finished.

/*error msg ond*/

this is your reply to one of post

Overflow error means the solver has diverged big-time. You need to improve the numerical stability. This could be improve mesh quality, better initial conditions, improperly set boundary conditions or physics. On rare occasions you need double precision numerics

what do you mean by improve numerical stability?

for initial I used steady state res file and started run which completed 100 iterations then stopped solver. After I continued same run but ends with above error.

i used expression for varying pressure at inlet
memory allocation factor= 1.1

Thanks in advace.

ghorrocks February 21, 2012 17:19

Quote:

what do you mean by improve numerical stability?
Doing CFD without knowing what numerical stability is like driving a car with your eyes closed. You are not going to get very far. I strongly recommend you get a numerical modelling textbook and get a feel for how numerical equations are solved so you understand these concepts.

Have you considered your mesh quality? How suitable is your initial condition? Are your boundary conditions and physics correct? Have you tried double precision numerics? Have you tried a smaller time step?

mahesh_1402 February 23, 2012 04:09

i did meshing in icem cfd with mesh quality as given below

Min = 0.000696609, max = 1, mean = 0.673647743127
3851746 elements with the "Quality" diagnostic
0 elements for which this diagnostic is undefined
Histogram of Quality values
0.95 -> 1.0 : 578492 (15.019%)
0.9 -> 0.95 : 572927 (14.874%)
0.85 -> 0.9 : 256030 (6.647%)
0.8 -> 0.85 : 194666 (5.054%)
0.75 -> 0.8 : 191400 (4.969%)
0.7 -> 0.75 : 193965 (5.036%)
0.65 -> 0.7 : 191099 (4.961%)
0.6 -> 0.65 : 196635 (5.105%)
0.55 -> 0.6 : 227036 (5.894%)
0.5 -> 0.55 : 255466 (6.632%)
0.45 -> 0.5 : 201973 (5.244%)
0.4 -> 0.45 : 153878 (3.995%)
0.35 -> 0.4 : 113302 (2.942%)
0.3 -> 0.35 : 103463 (2.686%)
0.25 -> 0.3 : 95894 (2.490%)
0.2 -> 0.25 : 92426 (2.400%)
0.15 -> 0.2 : 84444 (2.192%)
0.1 -> 0.15 : 68100 (1.768%)
0.05 -> 0.1 : 59865 (1.554%)
0.0 -> 0.05 : 20685 (0.537%)


due to model complexicity i can not improve mesh quality. i used prism meshing.

by using this i gave steady state run

this are images of run.

http://www.mediafire.com/download.php?wx5fqhax3xajxvv
http://www.mediafire.com/download.php?vmyolav9vhqqg5y

i used k-epsilon first but error occurs so as read on forum i changed timesteps to smaller one with double precision but then also it fails.

at inlet condition its considering as opening type boundary instead of inlet one.

Zigainer February 24, 2012 10:10

Quote:

Originally Posted by mahesh_1402 (Post 345856)

0.15 -> 0.2 : 84444 (2.192%)
0.1 -> 0.15 : 68100 (1.768%)
0.05 -> 0.1 : 59865 (1.554%)
0.0 -> 0.05 : 20685 (0.537%)

This is more than 6% with quality <0.2 (which is a minimum for CFX). So that could actually be a problem.
What about the other mesh paramters? Min angle, mesh expansion factor, aspect ratio? Where are these bad cells positioned? Have you check where your max residuals are?

ghorrocks February 25, 2012 06:50

Have you tried a smaller time step?

mahesh_1402 March 2, 2012 22:25

sorry for late reply.
there was problem in physics. now its solved. run under progress.

i gave run for total time= 10 sec and time steps=50*0.1,25*0.2

do i have to run for even for smaller time steps?

ghorrocks March 3, 2012 06:17

The normal practise for CFD analysis is:
1) Set the basic simulation up so all the physics seems to be modelled and doinjg believeable things.
2) Do sensitivity analysis on all adjustable parameters to get the simulation accurate.

It looks like you have completed step 1. Now you have to do step 2. This means you need to show your convergence, mesh, time step size, advection scheme and any other adjustable parameters are correctly set to give an accurate simulation.


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