Learning Forum

[JD_JN]

Hello everyone!

I am running a 2d transient axisymmetric simulation on ANSYS FLUENT 2019 R3 owned by my college (Intel Xeon E5-1650 Quadro K620 Windows 8.1 Pro).

The calculations were going on well, until recently it encountered this error of 'out of scheme heap space'. I tried running case and data files of previous flow times and they all run well - up to the point when it reaches a flow time of 9.26 milli-seconds post which FLUENT stops and throws out this error.

I tried the solutions shown in the posts: /forum/discussion/10380/error-out-of-scheme-heap-space? and /forum/discussion/comment/17613#Comment_17613 but they do not help.

I even tried to launch FLUENT via command terminal as suggested in : /forum/discussion/comment/17613#Comment_17613 , but when providing an additional 'h' parameter in the launch command (fluent 2ddp -t6 -h50000) FLUENT gets called but does not launch. If the 'h' parameter is removed from the command line then it launches FLUENT - which does not serve the required purpose.

The error log image is provided below:

Out of scheme heap space_error sect.png

[Rob]

Please add the image into the post, staff are not permitted to open or download attachments. n

[JD_JN]

Sure! nHere is the image of the error log.n

[Rob]

Try the command with -500000 as I think you've missed a 0 in the -h command:nnfluent 2ddp -t6 -h500000n

[JD_JN]

! Thanks a lot for the response. I tried adding an extra zero at the end, but unfortunately FLUENT still does not launch.n

[JD_JN]

Right. nSo after few days of trying to find a solution, I got it!! The solution to this error for me was by deleting the solution export. (oh the irony! )nI had enabled automatic solution export in FLUENT. Weird as this may seem, once I deleted the automatic solution export, the calculations have begun to run smoothly again!nI tried to create a new solution export with a different name, but it throws an error each time it writes the solution after 1 or 2 time steps. I have no idea why though.nFor now, the way forward is by deleting the automatic solution export. If someone figures out why this happens, please do let me know.n

[Rob]

Odd, I moved it here as it may be installation related and knows all about that. What time step are you up to? I'm wondering if you've hit a limit somewhere in the code for the number format. n

[JD_JN]

Array I've set a time step size of 1E-6. The flow time is in milli seconds, and FLUENT would throw an error when exporting the solution once it reached 9.26 milli seconds. nI haven't the faintest idea as to why it does that. So once I removed automatic solution export, it stopped complaining!nCome to think of it, I had also enabled append flow time with the solution export file name. Is that what was causing the issue?n

[Rob]

Possibly, depending on the format you could be running out of numbers (figures) at that point. I tend to use %t (time step) when saving data & images, more as a habit than anything else as %t has been an option since at least Fluent 5.n

[JD_JN]

Well in that case, why doesn't it throw an error when auto saving case and data files?n I've set that on automatic too, and it appends the data files with the latest flow time but doesn't throw an error while auto saving and writing it. ?n

[Rob]

Good point. I'll talk to a developer. n

[JD_JN]

Awesome! Much appreciatedn

[E G]

Hi, I am having the same problem. Where is the automatic solution export in FLUENT so that I can delete it? This is not the same as autosaving data files for a transient solution?

[Rob]

Autosave will give case & data files to allow a restart of Fluent. Those files can also be read into Fluent for post processing, and into other tools if you really want to.   Auto export is possibly cdat or similar format that's only useful for post processing: Fluent can't use those files for a restart, and may not be able to read them at all. 

Note, running out of Heap/Stack is unusual in the more recent releases, and I've not seen a case from the commercial client base in several years. Check machine RAM; how many monitors have you got? Any UDFs?  

[E G]

Thank you for the explanation, Rob.
I have 2 report monitors and no UDFs. How do I delete the automatic solution export like JD_JN did?

[Rob]

Are you writing out flowtime or timestep on the files? I don't remember what I got back on our side, but I also can't comment on internal emails.