CFD Online Discussion Forums

CFD Online Discussion Forums (
-   OpenFOAM Post-Processing (
-   -   functionObject file format (

akidess February 18, 2012 13:36

functionObject file format
I can't seem to find a way to save the output of the functionObject "cuttingPlane" into a binary file. The default seems to be ASCII, which wastes disk space. Does anyone know if it's possible to change the file format?

wyldckat February 18, 2012 16:47

Hi Anton,

Nope! According to the code at "OpenFOAM-2.1.x/src/sampling/sampledSurface/writers", it's all hard coded as ASCII only. There is a proxy system, but it only sends the surface points to the writer.

The closest you can get is pack things via another functionObject: - this way you even pick the format you want ;) well, compression only :(

Best regards,

akidess February 20, 2012 07:55

Thanks Bruno! It's funny it's hard-coded to ASCII, because the writer classes do support binary files (at least src/conversion/ensight does). So for now I just hard-coded binary instead of ASCII, and it works fine :)

wyldckat February 20, 2012 09:52

Hi Anton,

I think they hard-coded things this way, because the normal writers are for volumes only :(

Best regards,

akidess February 22, 2012 15:19

Sorry, I didn't quite get that. Can you explain what you mean with volumes only and normal writers?

wyldckat February 22, 2012 16:48


Originally Posted by akidess (Post 345793)
Sorry, I didn't quite get that. Can you explain what you mean with volumes only and normal writers?

The idea I was trying to convey is as follows: the simulation cases done with OpenFOAM usually focus only on the volume mesh and the patches. When we want to generate a sampled surface, even when directly coded in a solver or utility, the resulting surface data isn't as good looking as the volume mesh.

Here's an example of what I'm talking about:
If you read the whole thread, you'll understand that the sampled surface cannot be represented as nicely as a patch surface, simply because said sampled surface is only represented by points! :(

I think this is why the functionObject "cuttingPlane" is using dedicated and hard-coded surface writers, instead of using an already existing "driver".

akidess February 24, 2012 06:25

Actually, I just noticed that the sample 'sampleDict' changed between 2.0.x and 2.1.x. The latter now includes an entry


39 // optionally define extra controls for the output formats
 40 formatOptions
 41 {
 42    ensight
 43    {
 44        format  binary;
 45    }
 46 }

which is exactly what I was looking for!

wyldckat February 24, 2012 09:51

Nice! I should have looked deeper into this :)

All times are GMT -4. The time now is 04:21.