Help with efficiently exporting data

nick.l.thomas · November 27, 2018, 23:40

I am looking for feedback and suggestions on the way I'm currently exporting transient data. I am analyzing flow over rotating cylinders and want primarily to retain pressure, velocity in stn frame, vorticity, and lift and drag coefficient data.
In Pre I am set to output cgns and trn files every .2s, although the cgns from this proved to be difficult to use since it only exports surface data. My batch code currently has the following:

cfx5solve to export the .trn

cfx5export to export .cgns for the entire domain every .2s. -user "3" to output the third level of data, including vorticity which I need

cfx5mondata to export lift and drag coefficient data (monitors) to a .csv

I feel that I'm being very inefficient as I wind up with very large amounts of data simply trying to get a few variables. I'm importing all the .cgns files to Tecplot at once to get the animations and contours, which takes a lot of time (maybe necessary?). And I wind up with a million parameters I don't want or need (from the "-user "3"" command to get vorticity data).

I also still don't fully understand the need for .trn files. From what I read they are essentially backup files for transient runs that are used for restarts - but can't a restart be done simply using the .res file?

I'm pretty new to using batch code and getting transient results with CFD so forgive me if I'm missing something obvious, but any advice for simplifying this process while still getting the results I need?

ghorrocks · November 28, 2018, 00:26

It all depends on exactly what data you need in your post processor. It looks like in your case you could greatly reduce the data quantity by:
* using "selected variables" only in the trn files
* including the surfaces of interest in the trn files only
* importing CFX trn or res files directly into Tecplot rather than cgns

nick.l.thomas · November 28, 2018, 13:23

Thanks for the response Glenn. One question - I am able to import the res file directly to Tecplot but it only contains the final timestep. I can't figure out how to load any of the .trn files alone, or in conjunction with each other or the .res file. Is there a good way to do this?

ghorrocks · November 28, 2018, 16:52

I am guessing here, but Tecplot can probably read the trn files if you use the "include mesh" option when you set up the CFX job in the Output tab.

November 27, 2018, 23:40	Help with efficiently exporting data	#1
nick.l.thomas New Member Nick Thomas Join Date: Sep 2018 Posts: 27 Rep Power: 7	I am looking for feedback and suggestions on the way I'm currently exporting transient data. I am analyzing flow over rotating cylinders and want primarily to retain pressure, velocity in stn frame, vorticity, and lift and drag coefficient data. In Pre I am set to output cgns and trn files every .2s, although the cgns from this proved to be difficult to use since it only exports surface data. My batch code currently has the following: cfx5solve to export the .trn cfx5export to export .cgns for the entire domain every .2s. -user "3" to output the third level of data, including vorticity which I need cfx5mondata to export lift and drag coefficient data (monitors) to a .csv I feel that I'm being very inefficient as I wind up with very large amounts of data simply trying to get a few variables. I'm importing all the .cgns files to Tecplot at once to get the animations and contours, which takes a lot of time (maybe necessary?). And I wind up with a million parameters I don't want or need (from the "-user "3"" command to get vorticity data). I also still don't fully understand the need for .trn files. From what I read they are essentially backup files for transient runs that are used for restarts - but can't a restart be done simply using the .res file? I'm pretty new to using batch code and getting transient results with CFD so forgive me if I'm missing something obvious, but any advice for simplifying this process while still getting the results I need?

November 28, 2018, 00:26		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,705 Rep Power: 143	It all depends on exactly what data you need in your post processor. It looks like in your case you could greatly reduce the data quantity by: * using "selected variables" only in the trn files * including the surfaces of interest in the trn files only * importing CFX trn or res files directly into Tecplot rather than cgns __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

November 28, 2018, 16:52		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,705 Rep Power: 143	I am guessing here, but Tecplot can probably read the trn files if you use the "include mesh" option when you set up the CFX job in the Output tab. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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November 28, 2018, 13:23		#3
nick.l.thomas New Member Nick Thomas Join Date: Sep 2018 Posts: 27 Rep Power: 7	Thanks for the response Glenn. One question - I am able to import the res file directly to Tecplot but it only contains the final timestep. I can't figure out how to load any of the .trn files alone, or in conjunction with each other or the .res file. Is there a good way to do this?