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-   -   Saving entire transient simulation data for postprocessing. (https://www.cfd-online.com/Forums/star-ccm/96469-saving-entire-transient-simulation-data-postprocessing.html)

hamzamotiwala January 24, 2012 04:36

Saving entire transient simulation data for postprocessing.
 
Hello everyone,

I wanted to know if it was possible to save the entire simulation data for doing the post processing. I mean right now, I define what I want to analyse in preprocessing and in case I forget to create monitors and plots for some parameters I have to run the simulation all over again. Is it possible to just run the simulation and do whatever postprocessing I want later? I know the output file would be huge but I dont have any hard drive issues here so its not a problem. :)


cheers!
Hamza

willimanili January 24, 2012 09:36

The only way i know is to create monitors which collect the data for every timestep or every second, third ... timestep. You are able to export the monitor as an table after your simuation has finished.
Maybe you can also write an macro which fills up a table of all the data you are interested in for every timestep. But i dont have experience in writing macros.

Josh January 24, 2012 20:51

If you're not concerned about disk space or convergence time, you could set Auto Save so that your simulation file is saved every n timesteps and set a very large Max Autosaved Files value. Then you could go back and use a macro to extract whatever value you're interested in from all the .sim files.

I'm sure there's an easier way than this, but it's all I can think of for now.

Josh January 24, 2012 21:12

Look into "Calculating a Moving Average" using monitors.

Orden February 2, 2012 11:02

You can use the "Auto Export" feature, which saves your chosen scalars, vectors etc in the whole domain or in parts of it.
This can be done with a specified frequency and into a number of different formats. These files can then be imported into a 3rd party software which handles timeresolved data.

Hope this helps.

hamzamotiwala February 23, 2012 06:26

Thanks a lot Josh and Johan! I will check it out.

hamzamotiwala February 27, 2012 03:52

Hey Johan,

I tried the auto export feature and it works fine but the output file is just too huge. I mean, I was expecting like 20Gb but it was over 100Gb. I am doing an intercooler simulation and I run 8 to 10 cycles of a given input data set. I am only interested in the solution data from the last cycle. Is there a way to export data only from a given iteration number, i.e. the beginning of the last cycle?

Cheers,
Hamza

P.S. I might have selected way too many variables for the export. may be thats why the file was so huge, still I would like to export only the last cycle data.

abdul099 March 4, 2012 16:02

You can't expect to save the full set of results in a tiny file! When you're using autosave, it will save a complete sim-file every time the save is triggered. So it should be easy to calculate the amount of data, and that's usually a huge amount.

What might help you is to use v7.02 which will be released in the next two weeks ish. This version contains the first release of transient postprocessing which is better suitable for your problem than saving the whole sim-file after every time step. But you still need to think in advance which data to export, otherwise your hard disk still might be filled up pretty quick.

hamzamotiwala March 5, 2012 02:22

Thanks abdul that explains a lot. :)

and thanks for the tip too.

best regards,
Hamza


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