Learning Forum

[meljin]

I have run my files in Fluent for more than 512000 cells. It worked for many files. But, frequently it so happens that Fluent gives the below error message.

Error at host: This is an educational executable, and can only be used

with cases containing less than 512000 cells.

 

Please exit this fluent session and start another session to continue.

 

Could anyone kindly share the reason and the correction method?

 

Thank you in advance

 

[peteroznewman]

512,000 cells is the limit for the free Student license of Fluent.  If you have a Student license and happened to run with more, that is a bug and you got lucky.

The correction is to uninstall the Student software and install a paid Research or Commercial license that has an unlimited number of cells.

 

[meljin]

Hello

I have paid licenses and not a student license.

A question. What error message would Fluent give when we open a case and data file having more than 512000 cells, given all the available licenses are in use by other users?

[Rob]

You see the error you posted. If all licences were taken you'll get an error from the TUI saying something about all licences are taken or in use. In your case, the Research key(s) are all in use and the licence manager is set to then pick up the next available option which is Teaching (much the same functionality as Student). Teaching can only deal with 512k cells. 

[meljin]

Thank you so much. Also, another peculiar case is when four licenses out of the five are used. On checking the license status, it switches between four licenses as being used (expected) and at other times five licenses as being used though the fifth license is not used.

Could you please let me know why this happens?

[Rob]

That may depend on the system: licences are used/released and checked at slightly different intervals. I have 10 Fluent licences on my PC, but if I open/close several very rapidly (typically when testing an unstable model) I occasionally only have 5 available. 

[meljin]

Hello

Apologies if I have understood this wrong. If I have 4 different simulations running, it means I am using 4 licenses. As long as I don't stop these 4 simulations, I would be using 4 licenses. I should still be able to use the 5th license when I have a total of 5 licenses rite? But, I get this 512K cells limitation as error when I open Fluent to load my 5th case and data.

Could you please help me understand when a license is exactly used?

[Rob]

If you are using four licences and there is a fifth free then you can use it. If you open/close sessions quickly you may find it takes the licence manager a few minutes to catch up. 

However, have you checked someone else isn't using the fifth key? 

[meljin]

Hello

Apologies! I should have mentioned this in an earlier thread.

I was actually submitting my simulations to a different server to increase the speed. While checking the Ansys license status, I found that a single node was repeated twice for a particular job. Realized that specifying "processing options" as parallel in the startup window for Fluent would provide a single node access to multiple processors at the vendor's server. And each processor consumes one license which is why a single simulation might use multiple licenses (one for each processor).

I am not quite sure how far the above reasoning is correct. Kindly correct me if I am wrong.

And to answer your question, no other person is using the 5th license.

[Rob]

Parallel should use up to 4 cpu from the solver key, and then you need HPC packs or a Workgroup.  Very old licences of Fluent used to work as solver or parallel keys, but those should have been removed in about R13: they date back to when parallel was rare as no one had hardware with many cpu's. 

If you're launching onto another machine/server, can you check the licence availability to that unit. You may find it's not seeing the research key. 

[meljin]

Hello

Thanks a lot for your help.

I have checked. I was actually using 8 processors for a single job which resulted in consuming 2 licenses.

[Rob]

Glad it's working. That's a very odd licence set up: please contact the local team (use contact us on ansys.com & your Uni address) as you may benefit from some updates! 

[meljin]

I agree, that's an odd setup. I guess I have got it wrong because I can see situations wherein it's against the assumption I made. There is something missing. I'll contact the local team.

You have been very helpful. Thank you.