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Old   December 23, 2012, 14:26
Question Calculate a quantity based on another quantity solved by Openfoam.
  #1
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Dear All,

I would like to calculate and output a quantity based on a scalar and added the following lines in createFields.H:

volScalarField vc
(
IOobject
(
"vc",
runTime.timeName(),
mesh,
IOobject::READ_IF_PRESENT,
IOobject::AUTO_WRITE
),
0.1*mag(fvc::grad(c))*mag(fvc::grad(c))
);


I added several lines to solve the goeverning equation to obtain the scalar fields c. I can confirm that the solutions of c is correct. However, for vc, I found that the above lines did not work at all. Does anybody know what is the problem behind it?

Thank you very much.
h
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Old   December 23, 2012, 19:13
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  #2
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Fumiya Nozaki
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Hi,

Do you update the vc value at each time or iteration?
vc = 0.1*mag(fvc::grad(c))*mag(fvc::grad(c));

Best regards,
fumiya
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Old   December 23, 2012, 19:18
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Hi,

that quantity should be calculated each time step, but I found that its value always failed to be updated suing the expression. I did not figure it out about this. Thank you very much.

best regards,
h
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Old   December 23, 2012, 19:33
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  #4
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Fumiya Nozaki
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Hi,

I think you can update the vc field at each time step
if you add the following line in the time loop.
Code:
vc = 0.1*mag(fvc::grad(c))*mag(fvc::grad(c));
Best regards,
fumiya
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Old   December 23, 2012, 19:42
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  #5
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Hi,

Thank you very much for your suggestion. If I adopt your method, but if I still want to output this quantity, maybe I need to add the following lines in createFields.H:

volScalarField vc
(
IOobject
(
"vc",
runTime.timeName(),
mesh,
IOobject::READ_IF_PRESENT,
IOobject::AUTO_WRITE
),
mesh
);

But When I do this, compilation is successful, but when I run the code, some error information appears as follows:

#0 Foam::error:rintStack(Foam::Ostream&) in "/users/abc/OpenFOAM/OpenFOAM-2.1.1/platforms/linux64Gcc45DPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/users/abc/OpenFOAM/OpenFOAM-2.1.1/platforms/linux64Gcc45DPOpt/lib/libOpenFOAM.so"
#2 ?? in "/lib64/libc.so.6"
#3 Foam::divide(Foam::Field<double>&, Foam::UList<double> const&, Foam::UList<double> const&) in "/users/abc/OpenFOAM/OpenFOAM-2.1.1/platforms/linux64Gcc45DPOpt/lib/libOpenFOAM.so"
#4 void Foam::divide<Foam::fvsPatchField>(Foam::FieldField <Foam::fvsPatchField, double>&, Foam::FieldField<Foam::fvsPatchField, double> const&, Foam::FieldField<Foam::fvsPatchField, double> const&) in "/users/abc/OpenFOAM/OpenFOAM-2.1.1/platforms/linux64Gcc45DPOpt/lib/libcompressibleRASModels.so"
#5 Foam::tmp<Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> > Foam:perator/<Foam::fvsPatchField, Foam::surfaceMesh>(Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::tmp<Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> > const&) in "/users/abc/OpenFOAM/OpenFOAM-2.1.1/platforms/linux64Gcc45DPOpt/lib/libcompressibleRASModels.so"
#6 Foam::fv::backwardDdtScheme<Foam::Vector<double> >::fvcDdtPhiCorr(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&) in "/users/abc/OpenFOAM/OpenFOAM-2.1.1/platforms/linux64Gcc45DPOpt/lib/libfiniteVolume.so"
#7 Foam::tmp<Foam::GeometricField<Foam::flux<Foam::Ve ctor<double> >::type, Foam::fvsPatchField, Foam::surfaceMesh> > Foam::fvc::ddtPhiCorr<Foam::Vector<double> >(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<Foam::flux<Foam::Vector<doubl e> >::type, Foam::fvsPatchField, Foam::surfaceMesh> const&) in "/users/abc/OpenFOAM/abc-2.1.1/platforms/linux64Gcc45DPOpt/bin/cmcPimpleFoam"
#8 main in "/users/abc/OpenFOAM/abc-2.1.1/platforms/linux64Gcc45DPOpt/bin/cmcPimpleFoam"
#9 __libc_start_main in "/lib64/libc.so.6"
#10 Foam::UOPstream::write(char) in "/users/abc/OpenFOAM/abc-2.1.1/platforms/linux64Gcc45DPOpt/bin/cmcPimpleFoam"
Floating point exception
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Old   December 23, 2012, 19:54
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  #6
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Fumiya Nozaki
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Hi,

How about if you use the code in your post #1 with my suggestion?

In the createFields.H

volScalarField vc
(
IOobject
(
"vc",
runTime.timeName(),
mesh,
IOobject::READ_IF_PRESENT,
IOobject::AUTO_WRITE
),
0.1*mag(fvc::grad(c))*mag(fvc::grad(c))
);


and in the time loop
vc = 0.1*mag(fvc::grad(c))*mag(fvc::grad(c));

Best regards,
fumiya
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Old   December 23, 2012, 20:00
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  #7
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Hi fumiya,

I tried the method mentioned post #6, but the error info is totally the same as those in post #5. I do know why these errors appear. Do you have further suggestions?

best
h
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Old   December 23, 2012, 20:30
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  #8
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Fumiya Nozaki
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Hi hz283,

I have confirmed that the scalarTransportFoam added the lines in the
post #6 runs well without error.

If you can post the solver and case, I think you will get further suggestions.

Best regards,
fumiya
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Old   December 24, 2012, 09:36
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Hi fumiya,

In the createFields.H, if I use the following instead of IOobject, the code can run successfully:

volScalarFields("vc", 0.1*mag(fvc::grad(c))*mag(fvc::grad(c))).

This indicates that the Input/Output is not correct. But I still do not know about the cause.

Merry Xmas.
h
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Old   December 26, 2012, 15:17
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  #10
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Quote:
Originally Posted by fumiya View Post
Hi,

How about if you use the code in your post #1 with my suggestion?

In the createFields.H

volScalarField vc
(
IOobject
(
"vc",
runTime.timeName(),
mesh,
IOobject::READ_IF_PRESENT,
IOobject::AUTO_WRITE
),
0.1*mag(fvc::grad(c))*mag(fvc::grad(c))
);


and in the time loop
vc = 0.1*mag(fvc::grad(c))*mag(fvc::grad(c));

Best regards,
fumiya
Hi fumiya,

If I add the following lines in createFields.H:
volScalarField vc
(
IOobject
(
"vc",
runTime.timeName(),
mesh,
IOobject::READ_IF_PRESENT,
IOobject::AUTO_WRITE
),
0.1*mag(fvc::grad(c))*mag(fvc::grad(c))
);


But If I donot have the following lines in the time loop:
vc = 0.1*mag(fvc::grad(c))*mag(fvc::grad(c));

It seems that the quantity will only calculated once just in the beginning and will not be updated with the time advancement. Is my understanding correct about this?

Thanks.

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Old   December 27, 2012, 02:47
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  #11
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Fumiya Nozaki
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Hi hz283,

I think you are correct.
We have to add the following line
vc = 0.1*mag(fvc::grad(c))*mag(fvc::grad(c));

in the time loop in order to update the value vc.

fumiya
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