fluent journal file for carrying out LES
 

Hello Everyone

I am carrying out LES simulations in a HPC. For it I have to write the journal file. Should all the settings be written in the journal file or is it possible to give settings in Fluent and write a journal file having commands to only run ,initialize and write data. Consider following case :

(set! *cx-exit-on-error* #t)
rc wst.cas
/solve/init/init
it 100
wd wst.dat
exit
yes


Thank YOu

Can you copy settings from old case?

you could write a bc-file and then make a journal that read the settings to new case/mesh.

Certainly, I do it all the time. All the settings are stored in the case file.

You can specify your settings using a GUI, even the initialization, and then save it the .cas and .dat file. Then have a very simple journal file that basically does only the following:

rcd name
solve dual-time iterate 123123 10
wcd name ok

Many settings are much easier to specify using the GUI, if you have enough RAM to open your case!

THank you for your answer. How to read both .cas file and .dat file ?

Aside from read-case and read-data, there is also read-case-data. Similarly there is write-case, write-data, and write-case-data. The abbreviations for these are rc, rd, rcd, wc, wd, wcd.

When you use rcd and wcd, you only specify the rootname without the extension. I.e. rcd myfile instead of rc myfile.cas and rd myfile.dat. Fluent assumes the .dat file matches the rootname of the .cas file.

You also do not have to use rcd and wcd. You can still do rc followed by rd and wc followed by wd. This is useful when you want to read a .dat file that has a different name, i.e. when automatically saving after x iterations or time-steps. You usually have myfile-10000.dat.

Then you would do rc myfile.cas to read the original case file and then rd myfile-10000.dat to read the latest .dat file. Of course you can always rename myfile-10000.dat to myfile.dat, but some of us are lazy. =)

Thank you for your reply. I am a beginner in using the journal file. I created following journal file:

( set! *cx-exit-on-error* #t)

rc ICM-5-Setup-Output.cas.gz
rc ICM-5-1.cas.gz
rd ICM-5-100000.dat.gz

/solve/init/init
it 100000

wd ICM-5_Setup-Output.dat

exit

yes

But the computer says following error :
Cleanup script file is
/scratch2/x1334prj/fw/cleanup-fluent-sinbaram14.plsi.or.kr-48749.sh


gzip: ICM-5-Setup-Output.cas.gz: invalid compressed data--format violated

gzip: ICM-5-Setup-Output.cas.gz: invalid compressed data--format violated

I tried changing the files into .cas and .cas.gz but still it I get the same error.

When you read a .gz compressed file, Fluent will automatically invoke the gunzip utility to de-compress it. This type of message is output from the gunzip utility, it's actually not a Fluent error. It usually means your .gz files are corrupted or something like that. Try creating a new case file.

I tried to change the case file. I have interpolated data from previous simulations to this transient simulation.

When I dont interpolate the values Fluent only creates a ICM-5-Setup-Output.cas file. I have no problem running this with the script file :
(set! *cx-exit-on-error* #t)

rc ICM-5-Setup-Output.cas

/solve/init/init

it 100

wd ICM-Setup-Output.dat

exit

yes

When I interpolate the values fluent makes three files :
ICM-5-1.cas
ICM-5-1-00000.dat
ICM-5-Setup-Output.cas

But I can't run it with the script file :
(set! *cx-exit-on-error* #t)

rc ICM-5-Setup-Output.cas
rd ICM-3-1-00000.dat
/solve/init/init

it 1000

wd ICM-Setup-Output.dat

exit

yes

Also the output given is :
Cleanup script file is /home01/x1334prj/fl/cleanup-fluent-sinbaram11.plsi.or.kr-45388.sh

Why would you reinitialize and clear the solution after interpolating it by running /solve/init/init? There's probably plenty of messages in the terminal output that tell you exactly where the issue is.

Fluent doesn't automatically do these things. You are doing it. It seems you are using a script that you don't understand.

In batch environments, Fluent creates a cleanup script so the user can kill the process, in case it hangs. You don't need to tell us this is an output.

I'm not sure you are ready for LES if you are having basic difficulties running Fluent. You're also only doing iterate 1000, with no time-stepping. LES should involve time-stepping and you should be invoking the dual-time-iterate.

I have carried out LES simulation in my Lab Server.I used time stepping method. But I didn't have to run it with batch mode. Now In HPC, I am having to use it in batch mode which I don't have any idea using.Since its only a test file I kept the iteration of 1000. No, the terminal output doesn't have any messages. It is blank. I need to learn using fluent in batch mode.

If possible please provide a good example of running fluent in batch mode.

Thank you

Batch mode is nothing special. It's simply fluent without a gui. You can type all these commands into the TUI in a regular session w/ a gui to test these things. You'll actually see the Fluent messages this way.

Are you running this in windows or unix? Based on your issues, I'm guessing you have a Windows HPC setup or a poorly setup unix configuration.

You probably forgot to pass the output argument that you used to launch Fluent. But since I have no idea what your HPC configuration is, I can only guess. For example, in unix you have the option to specify:

fluent 3ddp -g -i journal >& outputfile &

The >& outputfile & part would depend on your shell and could be slightly different from setup to setup.

If you are running HPC in windows.... Then you need to put
/file/start-transcript outputfile.something into your journal file. This writes the Fluent output to the outputfile.something so you can acually get some information. So far you are only getting the terminal output, i.e. the dos terminal in windows which does not capture the Fluent output, only the system commands.

Hello, thank you for your answer.
Writing script file based on bc-file looks very complicated. I also have to run it on a different computer.

Thank you for your answers. When using LES is it acceptable to use 1st order transient formulation ? Because we can use time stepping only in the 1st order transient formulation. it is said that LES requires 2nd order transient formulation with which time stepping can't be used .

Thank you for your answer. I am using Linux-based HPC.