[fanny]

Hi Artur. Thank you very much for that great tutorial. It helps very much !


I have two questions concerning the postprocessing functions (tutorial 09).



- Why we have a 0 directory inside the directory postProcessing ?



- How can I use the postProcess utility ? When specified without additional arguments, the postProcess utility should execute all function objects defined in the system/controlDict file for all time directories but I have the error message

--> FOAM FATAL ERROR:
request for volVectorField U from objectRegistry region0 failed
available objects of type volVectorField are
0()

From function const Type& Foam:bjectRegistry::lookupObject(const Foam::word&) const [with Type = Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>]
in file /home/ubuntu/OpenFOAM/OpenFOAM-7/src/OpenFOAM/lnInclude/objectRegistryTemplates.C at line 193.

FOAM aborting




Thank you !
Fanny

[Artur]

Hi,


The 0 folder follows OF convention whereby subsequent restarts or calls write data to a specific time (in this case iteration) directory. The utility doesn't even specify this explicitly, it gets done automatically. The only thing done here is appending the name of the object to the existing file names inside

Foam::wordList Foam::functionObjects::pipeCalc::createFileNames

.


I am not sure where the second error is coming from. The main point here is that the utility has been written to be executed in parallel with the solver and not after this has been run. Hence, it works fine within simpleFoam but apparently some fields do not get read properly when it is run with postProcess. My hunch is that the velocity field would need to be explicitly requested somehow, but it's beyond the scope of the tutorial as I intended it. If you do figure it out, please do share


Kind regards,


A

[fanny]

Thank you so much Artur for this quick and clear answer

[Artur]

Hello everyone,


I recently completed a tutorial on discretisation schemes after a request from the community. Hope you'll find it useful!


Happy foaming,


A
cellCentreValues.jpg tutorial15.jpg

[JunaidAhmad]

I have a question how can I explore member function of "volScalarField"

volScalarField T
(
    IOobject(
        "T",
        runTime.timeName(),
        mesh,
        IOobject::MUST_READ,
        IOobject::AUTO_WRITE),
    mesh
);

e.g.
the output of

Info<< T << nl;

is

dimensions      [0 0 0 1 0 0 0];


internalField   uniform 0;

boundaryField
{
    left_sides
    {
        type            zeroGradient;
    }
    right_sides
    {
        type            fixedValue;
        value           uniform 1;
    }
    empty
    {
        type            empty;
    }
}

the output of

Info<< T.dimensions()    << endl;

is

[0 0 0 1 0 0 0]

and output of

Info<<T.boundaryField()  << endl;

is

3
(
    type            zeroGradient;

    type            fixedValue;
    value           uniform 1;

    type            empty;

)

output of

forAll(T.internalField(), cellI)
{
    Info<<"T.internalField()["<<cellI<<"]: "<<T.internalField()[cellI]<<nl ;
    
}

is

T.internalField()[0]: 0
T.internalField()[1]: 0

Now question is how can i explor boundaryField name, or all other member functions from doxygen or any other user guide.

[Artur]

Hi,


I'm not really sure what you're asking - do you mean printing text representation of various objects / output of functions? If so, then there isn't much more to say than what you've just demonstrated, beyond that not every object has the relevant formatting functions included in its definition. If you want to know more about input/output in general, tutorial 01 is the place to look.


As this is a very generic question not related to the tutorials, please consider making a separate thread for it.


Happy foaming,


A

[JunaidAhmad]

Thanks for your response, I want to know a systematic way to explore attributes and functions of classes in C++ or openfoam. Like in python there is a dir() function. If there isn't then we need one. As I just started foam so was wondering if some senior can develop one.

[Artur]

Hmm, that seems like a pretty involved C++ question rather than an OpenFOAM-specific one, to be honest. I have no answer to it myself, I'm afraid. Personally, I tend to rely on the auto-generated dependency graphs like the one at the bottom of this page whenever I get stuck:
https://cpp.openfoam.org/v9/classFoa...ionCoeffs.html

[JunaidAhmad]

Thanks, can u also share a similar link for volScalarField. And a pdf for doxygen.

[Artur]

There's a list of all the objects on the left and a search button in the top right corner

[JunaidAhmad]

I figured that out , but thanks to your above link, I found it. Due to some reason my computer got stuck then I searched the volscalarfeild previously in that top right corner. Thanks for all your guidance I learned a lot.

[khool_chelsea]

I am using OpenFOAM -v1906. I am getting an error in compiling the solver.

Make/linux64GccDPInt32Opt/OFtutorial7.o: In function `main':
OFtutorial7.C:(.text.startup+0xaeb): undefined reference to `computeR(Foam::fvMesh const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::dimensioned<Foam::Vector<double> >)'
collect2: error: ld returned 1 exit status
/home/administrator/OpenFOAM/OpenFOAM-v1906/wmake/makefiles/general:140: recipe for target '/home/administrator/OpenFOAM/administrator-v1906/platforms/linux64GccDPInt32Opt/bin/ofTutorial7' failed

The library was compiled without any issue so the solver must have access to the function computeR(). I am attaching the Make(files and options) for solver.
For Solver,
Make/file

OFtutorial7.C

EXE = $(FOAM_USER_APPBIN)/ofTutorial7

Make/options

EXE_INC = \
    -I$(LIB_SRC)/finiteVolume/lnInclude \
    -I$(LIB_SRC)/meshTools/lnInclude \
    -IcustomLibrary

EXE_LIBS = \
    -lfiniteVolume \
    -lmeshTools \
     -L$(FOAM_USER_LIBBIN) -lcustomLibrary

For Library,

Make/file

customLibrary.C

LIB = $(FOAM_USER_LIBBIN)/libcustomLibrary

Make/options

EXE_INC = \
    -I$(LIB_SRC)/finiteVolume/lnInclude \
    -I$(LIB_SRC)/meshTools/lnInclude

LIB_LIBS = \
    -lfiniteVolume \
    -lmeshTools

Any ideas where i might be wrong?

[khool_chelsea]

Issue resolved. there was a syntax error in the definition of computeR.

[JunaidAhmad]

Originally Posted by Artur

There's a list of all the objects on the left and a search button in the top right corner

Dear Artur,
I finally got the hang of this top right corner button. Thanks for you guidance again.
I thought to let the new users like me to know how to go about to find there way using extended guide. Below is the problem statement and its solution.



Problem: I had a volScalarField T and I want to find the dx or delta x of first node in mesh from object T.
Here is the procedure.

volScalarField T(
    IOobject(
        "T",
        runTime.timeName(),
        mesh,
        IOobject::MUST_READ,
        IOobject::AUTO_WRITE),
    mesh);

I started by searching volScalarField in extended guide the search gave me

typedef GeometricField<scalar, fvPatchField, volMesh> volScalarField

This shows that volScalarField is an object of GeometricField.
I clicked on GeometricField it lead me to

GeometricField< Type, PatchField, GeoMesh > Class Template Reference

In GeometricField I found internalField() function

const Internal & internalField () const

this return internal object which is

typedef DimensionedField<Type, GeoMesh> Internal

this give us DimensionedField where I found mesh() function

const Mesh & mesh () const

this return a Mesh object

typedef GeoMesh::Mesh Mesh

Till this point it was straight forward and here comes the twist. I search Mesh in search bar for typedefs of extended guide and found

Foam::fvMesh::Mesh()
Foam::DimensionedField::Mesh()
Foam::GeometricField::Mesh()
Foam::SlicedGeometricField::Mesh()
Foam::GeoMesh::Mesh()
Foam::pointMesh::Mesh()
Foam::polyMesh::Mesh()
Foam::surfMesh::Mesh()

In one of basic programming notes I read that Mesh reside in fvMesh so I go to fvMesh and found a function

tmp< surfaceVectorField > delta () const

I clicked on surfaceVectorField which takes me to

typedef GeometricField<vector, fvsPatchField, surfaceMesh> surfaceVectorField

this show that delta() is tmp<surfaceVectorField> type template which is a GeometricField temporary object. in

tmp< T > Class Template Reference

there I found

T * ptr () const

pointer of GeometricField type. which contains internalField function which we can access using internalField()[0].x()
Using all the knowledge above we can print the dx by the following expression.

Info << T.internalField().mesh().delta().ptr()->internalField()[0].x()<< nl;

PS: Dear Seniors if you can suggest a better way of doing this please guide.

[Artur]

Dear All,


I have updated the tutorials to work with OpenFOAM 9. The changes required were pretty minimal - the only part that was significantly affected was tutorial 12 which used to use the old fvOption infrastructure that has now become fvModels.


I have also added a new tutorial originally contributed by Ramkumar that demonstrates how an existing flow solution can be used in order to perform very simple Lagrangian particle tracking. This particular topic is quite dear to me (which you'll know if you've read my thesis ), and I'm hoping I can build on this tutorial in the future.


As always, happy foaming!


Artur

[irengclenk]

Hi Arthur,

First of all, thank you so much for the exercise, very helpful.
I am a beginner and use your exercises to learn Openfoam programming

I'm currently doing postprocessing exercise (Tutorial 9) using OF2012.
However I got this error:

pipeCalc.C:71:31: error: no matching function for call to \u2018Foam::functionObjects::pipeCalc::file(const label&)\u2019
             writeHeader(file(i), "Flow rate through face zone");
                               ^
In file included from /home/u0142217/OpenFOAM/OpenFOAM-v2012/src/OpenFOAM/lnInclude/logFiles.H:46:0,
                 from pipeCalc.H:43,
                 from pipeCalc.C:26:
/home/u0142217/OpenFOAM/OpenFOAM-v2012/src/OpenFOAM/lnInclude/writeFile.H:206:27: note: candidate: virtual Foam::OFstream& Foam::functionObjects::writeFile::file()
         virtual OFstream& file();

I noticed that there is no writeHeader function defined in the pipeCalc.H, then I gave a try to also include writeFile.H in it where we have writeHeader definition, but that doesnt work either. Or is it related to compatibility issue where your code only work for openfoam.org version?

Thanks!

[Artur]

Hi,


I haven't tried the code with other versions of OpenFOAM, but indeed this seems like something that might be related to compatibility issues. Worth having a quick go at installing the recommended version to double check, of course, but this tutorials has been around for a while so it's unlikely to not function properly.


BEst wishes,


A

[Bill_Yang]

Dear all,

I am a new user of openfoam. This is a very good tutorial for learning openfoam programming. I am writing this reply just to show the experience or issue I have when running the tutorial.

1) openfoam and ubuntu
I am using openfoam 8 and windows 10 based ubuntu 20.

2)
(tutorial 00, helloworld)
I type in the following command to run the case at the top-level directory:
: wmake
: ofTutorial0

The case is running OK.

3)
(tutorial 01, inputoutput)
I type in the following command to run the case at the top-level directory:
: wmake
: ofTutorial1

There is an error. It reminds me there is no mesh files found.
This is how I solve this error (may be a stupid way):
: So, I enter the testCase directory, then type: blockMesh
: Then I go back to the top-level directory and copy all the case files into the top-level directory.
: run 'ofTutorial 1' again.
The tutorial is running OK.

I think there should be a better way to do this. If anyone else can share this would be very useful.
A sgguestion from Artur and it works for me:

./Allwmake
cd testCase
./Allrun

For my case, I need to do this following

chmod +x Allwmake
./Allwmake
cd testCase
chmod +x Allrun
./Allrun

4)
(tutorial 02, command line argument and options)
This following codes work for me:

chmod +x Allwmake
./Allwmake
cd testCase
chmod +x Allrun
./Allrun

You can also try to input any other optional command lines according to the tutorial.
5)
(tutorial 03, understand the mesh)
The above code works.
Note: This tutorial presents how to get access the mesh info using the openfoam in-built class functions. It is very useful.

6)
(tutorial 04, basic field operations)
The above code works.
According to the suggestions in the tutorial, we could try to replace the for loop in the tutorial by first commenting the for loop command lines and then adding the following code:

/*replacement of the for loop*/
volScalarField r2 = (mag(dimensionedVector("x0", dimLength, originVector) - mesh.C()) / rFarCell);
volScalarField rR2 = (1. / (r2 + dimensionedScalar("tmp1", dimLength, 1e-12)));
scalar f2 (1.);
p = Foam::sin(2. * Foam::constant::mathematical::pi * f2 * runTime.time().value()) * rR2 * dimensionedScalar("tmp2", dimVolume, 1.)
			/ (dimensionedScalar("tmp3", dimTime, 1.) * dimensionedScalar("tmp3", dimTime, 1.));

7)
(tutorial 05, basic parallel computing)
Note: if you need to view the computational results, please remove the following code in Allrun:

rm -r processor* 2>/dev/null

I only have one issue with this tutorial. After running. I received the following error:

3 more processes have sent help message help-btl-vader.txt / cma-permission-denied
Set MCA parameter "orte_base_help_aggregate" to 0 to see all help / error messages

I will keep updating this.

[Artur]

Hi Bill,


Indeed, there is an easier way You can do everything by doing

./Allwmake
cd testCase
./Allrun

You may then check contents of each script to see precisely what is being done. In case of tutorial 1, that's just what you've figured out yourself:

blockMesh > log.blockMesh
ofTutorial1

Best wishes,


Artur

[Bill_Yang]

Originally Posted by Artur

Hi Bill,


Indeed, there is an easier way You can do everything by doing

./Allwmake
cd testCase
./Allrun

You may then check contents of each script to see precisely what is being done. In case of tutorial 1, that's just what you've figured out yourself:

blockMesh > log.blockMesh
ofTutorial1

Best wishes,


Artur

Thanks a lot Artur. That's very helpful. I just tried the commands and they work.