[santos]

Hello!

I know that it is possible to calculate a given field on a boundary, such as:

label inletPatchi = mesh.boundaryMesh().findPatchID(nameOfInlet);
scalar massFlux = sum(phi.boundaryField()[inletPatchi]);

It is also possible to get the field value of an arbitrary point as:

vector probePoint(x,y,z);
label probeCell = mesh.findCell(probePoint);

But is it possible to get the values of a field for a given plane? I need to get field values only for y=0.002. Any hint on how to do this in OpenFOAM?

Thank you!

Best regards,
José Santos

[dmoroian]

Hi Jose,
Maybe sampleSurface is what you want!

Dragos

[santos]

Hi Dragos

Thanks for your reply.

Yes sampleSurface works, in fact I am using it now to export the values to Octave to do the calculations I need. But I think it would be better if I could do it all in OpenFOAM!

José Santos

[ville]

Hi,
I would be interested in using the sampleSurface
utility for sampling cutplanes to a directory during a simulation so that I would not have to save all the 3D data and sample the cutplanes as a postprocessing task since the 3D files take a lot of space. Is this readily possible?
Thanks in advance!
Ville

[eugene]

It is possible, but not readily.

[ville]

Thank you for the reply!
What steps would be required to use the
related sampling dictionary
every dt intervals; would there be any possible piece of code for doing that? It would be quite
wonderful to try out since visualizing transient
phenomena in a time-resolved way becomes very
time consuming
if the animations are made out of large 3d data
sets.
-Ville

P.S. Since I couldn't find this on the forum:
An example of using the sampleSurface as a postprocessing tool is found in
~/OpenFOAM/OpenFOAM-1.4.1/tutorials/
solidDisplacementFoam/plateHole/system

[eugene]

You would have to integrate the sampleSurface utility into an application, or for more general use, into a function object. A fair amount of work unfortunately and I am not aware of existing applications that perform this task.

[maka]

will it work in parallel if we did so? If so I can try to do it since, I've been looking for a way to average fields in a set of planes during parallel run and this can do it if the sampling period is long enough to not to make the code slow.

[eugene]

sampleSurface works in parallel.

[dmoroian]

Saving a cell set that intersects a plane at runtime is presented here: cuttingPlane
It works in parallel, too.

Dragos

[lakeat]

Hi,

Since OpenFOAM already includes many third party software, why not add another one, say octave?

I am thinking these days, is it possible to do FFT with OpenFOAM? Because FFT utility is very common and very useful and ver important for post-processing, why not it is included?

It would be nice to see post-processing has the ability of Graphic showing and spectrum analysis etc.

Just a thought. \Daniel

[Pascal_doran]

Hi Daniel,

It seem that OpenFOAM 1.6 has FFT utility. See /usr/local/OpenFOAM/OpenFOAM-1.6/src/randomProcesses/fft

And I was wondering if you were able to use it. If yes could you show me how?

Thank you,

Pascal

[Bertrand]

I would be interested in this use as well, if anyone has information on how to implement a FFT on OpenFOAM probes.

Thanks!

[mani_v]

Originally Posted by santos

Hello!

I know that it is possible to calculate a given field on a boundary, such as:

label inletPatchi = mesh.boundaryMesh().findPatchID(nameOfInlet);
scalar massFlux = sum(phi.boundaryField()[inletPatchi]);

It is also possible to get the field value of an arbitrary point as:

vector probePoint(x,y,z);
label probeCell = mesh.findCell(probePoint);

But is it possible to get the values of a field for a given plane? I need to get field values only for y=0.002. Any hint on how to do this in OpenFOAM?

Thank you!

Best regards,
José Santos

Jose

I am new to openfoam. Can you tell where these lines can be added to calculate massflux at a boundary? It will be very helpful if you can show me an example.

[CedricVH]

Originally Posted by mani_v

Jose

I am new to openfoam. Can you tell where these lines can be added to calculate massflux at a boundary? It will be very helpful if you can show me an example.

You can better calculate the massflux through a boundary through a functionObject. Add this to your controlDict file to calculate the massflow through the inlet at write time.

functions
(
    mflow_inlet
    {
        type            faceSource;
        functionObjectLibs ("libfieldFunctionObjects.so");
        enabled         true;
        outputControl   outputTime;
        log             true;
        valueOutput     true;
        source          patch;
        sourceName      inlet;
        operation       sum;
        fields
        (
            phi
        );
    }
);

You can also achieve the same by post-processing the data using the command:

patchIntegrate -latestTime phi inlet