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writing solid body position to a file - sixdof issue

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Old   February 5, 2014, 13:13
Default writing solid body position to a file - sixdof issue
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When using the sixdof solver, how is it possible to write the time history of the body position to a file, like it is done with the forces?
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Old   February 26, 2014, 15:35
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hi,
unfortunately, i don't know how to do this well, but i'm also looking for a solution to this problem. Obviously, there is no ready-to-use functionObject for logging positions as there is for forces.
using other functionObjects, i got the demanded values, but in a very bad structure:

i used functionObject "writeRegisteredObject" in controlDict to write object "dynamicMeshDict":
a)
Code:
functions
{
    positions 
    {
        // Forcibly write registered objects

        type            writeRegisteredObject;
        functionObjectLibs ("libIOFunctionObjects.so");
	log 		yes;
        
        outputControl   timeStep;
        outputInterval  1;
        writeInterval   1;

        // Objects to write
        objectNames    ( dynamicMeshDict );
    } 
};

this produces folders and files for every single timestep

this means, i would get thousands of files like
caseRoot/80.01/uniform/sixDoFRigidBodyMotionState.gz
caseRoot/80.0199/uniform/sixDoFRigidBodyMotionState.gz
caseRoot/80.0298/uniform/sixDoFRigidBodyMotionState.gz
and so on, each containing a file like
b)
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.3.0                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "80.0199/uniform";
    object      sixDoFRigidBodyMotionState;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

centreOfMass    ( 3.3 0 0.1386375 );

orientation     ( 0.99807619 0 0.061999301 0 1 0 -0.061999301 0 0.99807619 );

velocity        ( 0 0 0.0045163445 );

acceleration    ( 1.3211615 -2.6233042 0.84606626 );

angularMomentum ( 0 -0.2529557 0 );

torque          ( 1109.8274 99.511973 -24.488035 );


// ************************************************************************* //
but does NOT create a logfile.
in fact, this is the information i was looking for, but i would prefer to get a single file like

c)
Code:
#time centreOfMass orientation velocity acceleration angularMomentum Torque
80.0199 ( 3.3 0 0.1386375 ) ( 0.99807619 0 0.061999301 0 1 0 -0.061999301 0 0.99807619 ) ( 0 0 0.0045163445 ) ( 1.3211615 -2.6233042 0.84606626 ) ( 0 -0.2529557 0 ) ( 1109.8274 99.511973 -24.488035 )
80.0298 ( ... ... ... ) (.. ... ... .. .. .. .. .. ..) (.. .. ..) (.. .. ..) (... .. ..)
80.0398 ( ... ... ... ) (.. ... ... .. .. .. .. .. ..) (.. .. ..) (.. .. ..) (... .. ..)
80.0497 ( ... ... ... ) (.. ... ... .. .. .. .. .. ..) (.. .. ..) (.. .. ..) (... .. ..)
like for forces output.

i know its just a matter of batch processing to collect all b)-files to a single c)-file, but it is not very clean to temporary overflood the case-directory with thousands of folders, containing folders, containig archives, containing files... before collapsing them all to one single text file.

So does anyone know a smarter solution to log these values in a single file at runtime?

regards
simon
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Old   February 26, 2014, 19:31
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Leonardo Antonio de Araujo
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have you tried to write as a "probe" in the controlDirect file?
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Old   February 26, 2014, 21:18
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probes does not work for my case, as it needs a "probeLocation", and centreOfMass is not inside any cell, because the simulated space lies outside the object - probe seems to take a value of a field in a specified location. Therefore, i tried to track the value of pointDisplacement in my centreOfMass location, with above conclusions..
but how to access motionState, which is not a field?
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Old   February 27, 2014, 05:22
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Leonardo Antonio de Araujo
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I'm having the same issue as well, I wish to track the amplitude and trajectory of the center of mass of a cylinder subjected to VIV. Check out this tool:
http://openfoamwiki.net/index.php/Co...omRegexp-files

it may be helpful.
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