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IDProjectCategoryView StatusDate SubmittedLast Update
0004058OpenFOAMBugpublic2024-02-27 15:042024-02-28 10:58
ReporterJohan Spang Assigned Towill  
PrioritynormalSeverityminorReproducibilityalways
Status resolvedResolutionfixed 
PlatformGNU/LinuxOSOtherOS Version(please specify)
Product Version11 
Fixed in Version11 
Summary0004058: cylindricalFunctionObject rendering incorrect results
DescriptionI am using the cylindricalFunctionObject to study the radial, tangential and axial components of U in a rotodynamic case (looking at the components of the generated 'cylindrical(U)' vector field in paraview). I noticed that something is wrong with the radial and tangential components. I traced the problem down to a dependence on the axial distance of each cell centre from the origin. My case uses the incompressibleFluid solver and contains an MRF zone.
Steps To ReproduceTo replicate with a simple 2D-case:

* Copy tutorials/incompressibleFluid/mixerVessel2DMRF to a temporary directory
* Run the Allrun script in the copied mixerVessel2DMRF folder
* Optionally, run the command 'touch test.foam' inside the mixerVessel2DMRF folder (for opening in paraview later)
* Make two new copies of the local mixerVessel2DMRF folder (including the generated solution data), name them with -1 and -2 extension. Now the temporary folder contains the following:
   mixerVessel2DMRF
   mixerVessel2DMRF-1
   mixerVessel2DMRF-2
* Navigate to the mixerVessel2DMRF-1 directory
* run transformPoints "translate=(0 0 0.1)"
* Navigate to the mixerVessel2DMRF-2 directory
* run transformPoints "translate=(0 0 0.2)"
* save the attached postProcessDict to the temporary folder
* inside each of the 3 cases run 'foamPostProcess -dict ../postProcessDict' (this will run the cylindricalFunctionObject and output the cylindrical(U) vector field for all time steps)
* Visualize the 3 different cases and compare mag(U) with mag(cylindrical(U)) - see attached image for an example that shows the problem.

The results are only as expected for the base case where z = 0 for all cells.
Additional InformationIn src/functionObjects/field/cylindrical/cylindricalFunctionObject.C:

Foam::tensor Foam::functionObjects::cylindrical::R(const vector& p) const
{
    vector dir = p - origin_;
    dir /= mag(dir) + vSmall;

    const vector axis = axis_/mag(axis_);
    const vector r = dir - (dir & axis)*axis;

    return tensor(r, axis^r, axis);
}

Should not r be normalized?

replacing:
    const vector r = dir - (dir & axis)*axis;

with:
     vector r_ = dir - (dir & axis)*axis;
     const vector r = r_ / (mag(r_) + vSmall);

Gives the expected results, as shown in the right column in the attached image. It also produces the expected results in my real world 3D case.

A side note:
src/meshTools/coordinateSystems/coordinateRotation/cylindrical.C seems to be implemented in a similar way, but I have not tested if it has any issues.
TagsNo tags attached.

Activities

Johan Spang

2024-02-27 15:04

reporter  

postProcessDict (961 bytes)    
/*--------------------------------*- C++ -*----------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  11
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
FoamFile
{
    format      ascii;
    class       dictionary;
    location    "system";
    object      controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //



functions
{

    cartesianToCylindrical
    {
        type        cylindrical;
        libs        ("libfieldFunctionObjects.so");

        origin      (0 0 0);
        axis        (0 0 1);

        field       U;

        writeControl    outputTime;
        writeInterval   1;
    }
}
// ************************************************************************* //
postProcessDict (961 bytes)   
visualization.png (171,280 bytes)   
visualization.png (171,280 bytes)   

will

2024-02-28 10:58

manager   ~0013202

Thanks for the report. Fixed in v11 and in dev.

https://github.com/OpenFOAM/OpenFOAM-11/commit/bc5adc26e6fac70447370342d4a48fc3481eb993
https://github.com/OpenFOAM/OpenFOAM-dev/commit/66835ba9a9d6a2631b52b51bf9b84353016076ef

Issue History

Date Modified Username Field Change
2024-02-27 15:04 Johan Spang New Issue
2024-02-27 15:04 Johan Spang File Added: postProcessDict
2024-02-27 15:04 Johan Spang File Added: visualization.png
2024-02-28 10:58 will Assigned To => will
2024-02-28 10:58 will Status new => resolved
2024-02-28 10:58 will Resolution open => fixed
2024-02-28 10:58 will Fixed in Version => 11
2024-02-28 10:58 will Note Added: 0013202