I would like to know, if it is possible in the post-proccesing phase, to get e.g. the stress or temperature in a CV, only by clicking on it or something similar. So far I have used the graph functionality, but I would like to know the "exact" numerical value.

Which postprocessor are you using?

I am using OpenDX(dxFoam) which follows with the FOAM 2.1 release.

Unfortunately no such facility is easily available in DX. I don't know whether other postprocessors provide this information.

In foam2.1 there is a command line utility 'lineSample' which can answer these questions for you. It needs a 'lineSampleDict' dictionary in the system/ directory of the case where you specify coordinates of the sampling lines, the fields to sample and the interpolation to use. It outputs a Matlab format file in a Matlab/ directory.

Below an example where I get a value somewhere at the top-right of the lid-driven cavity.

Note that this utility is currently under a drastic rewrite for Foam2.2

// lineSample dictionary

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

version 0.5;
format ascii;

root "/users/tfd/ljus/foam/run";
case "channel1";
instance "system";
local "";

class dictionary;
object sampleDict;


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

// cell: use only cell-centre value; constant over cell
// cellPoint: use cell-centre and vertex values
// cellPointFace: use cell-centre, vertex and face values
interpolationSchemes
{
p cellPoint;
U cellPoint;
}

/*
format of the sampling line:





*/
samplingLines
(
(0.099 0.099 0.005) (0.0991 0.099 0.005) 2
zero
"y"
"full"
);

scalarFields
(
p
);

vectorFields
(
U
);

// ************************************************** *********************** //

If you want to monitor a location during running you can also add 'probes' to your application. See e.g. the oodles application. The probe locations are specified in a constant/probeLocations dictionary and every time step the value at each of the locations will be written to a probes/ directory.

Thank you very much for your help!