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Why is droplet track file overwritten ?

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Old   July 10, 2007, 10:29
Default Why is droplet track file overwritten ?
  #1
mic
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Hi guys, problem with this file. I run the simulation, go on post processing, after having selected "read droplet properties from track file", it says "DROPLET DATA WILL BE LOADED FROM TRACK FILE XXX.trk - 0 DROPLETS READ FROM FILE", while in the simulation there were many many parcel ? In the guide i read: "The data in this file will be overwritten if the user generates post-processing particle tracks without first saving the droplet data." How can i save droplet data and avoid losing the solution ? Does it refer to droplet data before running the simulation ? many thanks, mic
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Old   July 10, 2007, 12:03
Default Re: Why is droplet track file overwritten ?
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Klaas Klever
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If you generate particle tracks (not the same as droplets!!!) during the post-processing, they can be saved in a file which by default is called XXX.trk. You can either change that or save your droplet track file with a different name.

If you have not generated particle tracks, but you still have trouble opening your track file, then your problem lies elsewhere. Did you check if your maxdrp is large enough? Which command did you use to load the droplet data? How large is your XXX.trk file?
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Old   July 10, 2007, 12:13
Default Re: Why is droplet track file overwritten ?
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mic
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ok, thanks klaas, i thought that particle tracks were generated from the .trk file, and wouldn't need an additional save in the same file !!! how can i save the droplet file with a different name ? i changed the value of maxdrp in order to run the simulation; i load the droplet data in post processing, then i open the track file (and usually i don't find nothing); xxx.trk file is now 80 kb, but it's binary and empty, i suppose; shall i set an appropriate Mb dimension in the droplet settings ? consider that i'm running with 72000 droplet, and it seems so large even to me... advices are welcome !!
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Old   July 11, 2007, 11:36
Default Re: Why is droplet track file overwritten ?
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Klaas Klever
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To save your *.trk file just copy it to a different name before you start generating any particle tracks.

There could be numerous errors for your empty track file. I think 72000 parcels are probably way too much but I don't really know your application.

Have you checked that your droplets really enter your domain?

Do you have evaporating droplets? Check if they evaporate instantaneously when they enter the domain.

Check the void fraction from your *.ccm file. This will tell you were you will find droplets in your domain if any.

Test your case. Get a converged solution of the flow field without droplets and just do an initial field restart from it with your droplets (use only a small number of droplet parcels, say 50). This should give you an approximate answer within a few iterations.

I hope this helps.
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Old   July 12, 2007, 10:00
Default Re: Why is droplet track file overwritten ?
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mic
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well, i did all you told me to do, but when i run the initial field restart, it gives a warning, a problem with LOAD, then it changes automatically the restart file name to the present one, it writes the geometry file, and in the GUIde panel, shows "analysis terminating"... how is it possible i can't run an analysis restart ?
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Old   July 12, 2007, 10:10
Default Re: Why is droplet track file overwritten ?
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Klaas Klever
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what did your void fraction show? Which version are you using? Have you spoken to CD-Adapco's support about your problem?
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Old   July 12, 2007, 11:46
Default Re: Why is droplet track file overwritten ?
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mic
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ok, it's now working, i wrote the geometry and problem file, then i runned the solver manually, it takes really only one iteration to get convergence. thank you. the void fraction will be modelled when i'll implement evaporation too. since i'm modelling fuel, i've to give manually the new scalar definition... thank you again, mic
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