[solimcfd]

Hi! Up till now I have been doing simulations in CFX with only 1 cell in the third coordinate direction. My results were pretty good so i wanted to check what would happen if I extend my model so as to make it three dimensional. I increased the thickness and added more cells in this direction. Using the same setup as before (timestep, accuracy ...) I have tried running this simulation but it always crashes on the first timestep in the first coefficient loop (floating point exception: overflow). Any ideas on what I should do to enable this 3D run?

[cfd_newbie]

Originally Posted by solimcfd

Hi! Up till now I have been doing simulations in CFX with only 1 cell in the third coordinate direction. My results were pretty good so i wanted to check what would happen if I extend my model so as to make it three dimensional. I increased the thickness and added more cells in this direction. Using the same setup as before (timestep, accuracy ...) I have tried running this simulation but it always crashes on the first timestep in the first coefficient loop (floating point exception: overflow). Any ideas on what I should do to enable this 3D run?

Hi,
Just the first step check - are you sure about the integrity of your 3D mesh ?
I mean do you see any error or warning messages for the new mesh ?

[solimcfd]

No, the mesh is is fine. I get no warnings or anything like that. It just crashes straight away. Should I change the setup for the 3D mesh or should it work with the same settings as before?

[ghorrocks]

Please post the output file around where it crashes.

[solimcfd]

Hi! The error looks like this:

+--------------------------------------------------------------------+
| Convergence History |
+--------------------------------------------------------------------+
+--------------------------------------------------------------------+
| Writing transient file 0.trn |
| Name : Transient Results 1 |
| Type : Selected Variables |
| Option : Time Interval |
+--------------------------------------------------------------------+

================================================== ====================
| Timestepping Information |
----------------------------------------------------------------------
| Timestep | RMS Courant Number | Max Courant Number |
+----------------------+----------------------+----------------------+
| 5.0000E-03 | 0.39 | 7.60 |
----------------------------------------------------------------------
================================================== ====================
TIME STEP = 1 SIMULATION TIME = 5.0000E-03 CPU SECONDS = 2.666E+01
----------------------------------------------------------------------
| SOLVING : Wall Scale |
----------------------------------------------------------------------
| Equation | Rate | RMS Res | Max Res | Linear Solution |
+----------------------+------+---------+---------+------------------+
| Wallscale-Bulk | 0.00 | 2.2E-05 | 1.1E-04 | 43.0 6.1E-01 ok|
+----------------------+------+---------+---------+------------------+
| Wallscale-Bulk | 3.25 | 7.1E-05 | 2.2E-03 | 33.6 9.0E-02 OK|
+----------------------+------+---------+---------+------------------+
| Wallscale-Bulk | 0.62 | 4.4E-05 | 1.6E-03 | 29.0 9.7E-02 OK|
+----------------------+------+---------+---------+------------------+
| Wallscale-Bulk | 0.87 | 3.8E-05 | 1.5E-03 | 29.0 8.8E-02 OK|
+----------------------+------+---------+---------+------------------+
| Wallscale-Bulk | 0.84 | 3.2E-05 | 1.2E-03 | 29.0 8.3E-02 OK|
+----------------------+------+---------+---------+------------------+
| Wallscale-Bulk | 0.90 | 2.9E-05 | 1.1E-03 | 24.3 9.8E-02 OK|
+----------------------+------+---------+---------+------------------+
----------------------------------------------------------------------
COEFFICIENT LOOP ITERATION = 1 CPU SECONDS = 7.928E+01
----------------------------------------------------------------------
| Equation | Rate | RMS Res | Max Res | Linear Solution |
+----------------------+------+---------+---------+------------------+

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

Details of error:-
----------------
Error detected by routine POPDIR
CRESLT = ILEG

Current Directory : /FLOW/NAMEMAP

[ghorrocks]

Start with a smaller initial time step or a more representative initial condition. This assumes you have set the simulation up correctly, of course.