CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   CFX (http://www.cfd-online.com/Forums/cfx/)
-   -   Hard drive storage and .cfx vs .def files (http://www.cfd-online.com/Forums/cfx/92396-hard-drive-storage-cfx-vs-def-files.html)

audrey September 13, 2011 09:09

Hard drive storage and .cfx vs .def files
 
Hi everyone,

This might be a silly question, but I couldn't find a clear answer, either in the manuals or the forums, so I thought I'd just ask.

Is there any important difference between the information contained in .cfx and .def files? I've been struggling with limited hard drive storage space (I know about all obvious solutions, here, like buying an external hard drive, but school regulations make these impractical - I would have to buy backed up storage on the university server which is on the expensive end for a project with no budget...)

To make a long story short, I'm trying to stretch my hard disk space and I noticed that .cfx and .def files can get pretty large. I've got loads of them, and I like to keep them in case I want to go back to a previous simulation setup, but I was wondering if there was a good reason to keep both .cfx and .def files for previously run simulations, or whether keeping just one of them would give me all the info I need. (I understand that in theory, all the info is printed in the .out file, but who wants to start from stratch every time...)

Thanks,
Audrey

stumpy September 13, 2011 10:01

I usually just keep the .def files. You can open a .def file in CFX-Pre then hit save to recover the .cfx file. The .def file only contains the info needed for the current run, so in some cases the .cfx file can contain additional information (e.g. materials and other library data that have been defined but not used), but this isn't usually a concern.

audrey September 13, 2011 10:05

Thanks! That makes sense. The extra stuff that has been defined but not used is actually more of a problem than a solution for me, because I keep realising that I forgot to update an expression or the properties of a material... I think I'll adopt the same strategy and only keep .def files. (I'll probably keep .cfx files for some of the most recent runs, just in case)

brunoc September 15, 2011 21:39

I think the only time a .cfx file is better then a def file is when you're working with a multiconfiguration setup and you have only one mesh (say, if you're setting a multiconfiguration run to start with a steady state simulation and then go transient). In that case the mesh is the same, and the .cfx file will only store one instance of it. The def (or mdef, for multiconfiguration definitions) file won't be a single file, but a folder filled with the different configrations generated.

An if your really have to save space, delete the res and keep the out file, so at least you know what you'll have to do to get to the same result.

bhatiadinesh September 16, 2011 00:34

One other instance where a CFX file is better than a def file is when you have multiple meshes which you have imported individully imported in CFX and have joined them using interfaces. In such a case if you need to replace only a single mesh file, then CFX file is your easy way out, coz in de4f you cannot perform this as .def file will show a single mesh.

-Dinesh

audrey September 16, 2011 06:19

Thanks, that's good to know. For now, I'm sticking to steady state simulations with a single mesh, so I think it's ok to keep only .def files. I've been keeping most .res files, but if I run out of space too quickly, I might start deleting the simulations that didn,t converge - I've got LOADS of those.......


All times are GMT -4. The time now is 00:52.