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How to get omega fields ?

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Old   October 19, 2009, 08:54
Default How to get omega fields ?
  #1
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John Deas
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Hi,

I am using OpenFOAM-1.5. I am doing RANS k-omega SST computations with a custom solver derived from simpleFoam and would like to manipulate fields of omega.

In createFields.H, there is

Code:
autoPtr<incompressible::RASModel> turbulence
(
    incompressible::RASModel::New(U, phi, laminarTransport)
);
and looking at the doc, I found that RASModel has no omega() method, while the kOmegaSST class which derives from RASModel has one.

I also found the declaration of New() which did not help me much:

Code:
//- Return a reference to the selected turbulence model
static autoPtr<RASModel> New
(
    const volVectorField& U,
    const surfaceScalarField& phi,
    transportModel& transport
);
I would like to know how can I access the method omega() corresponding to the turbulence model I am currently using.
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Old   October 19, 2009, 11:34
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Bernhard Gschaider
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Quote:
Originally Posted by johndeas View Post
Hi,

I am using OpenFOAM-1.5. I am doing RANS k-omega SST computations with a custom solver derived from simpleFoam and would like to manipulate fields of omega.

In createFields.H, there is

Code:
autoPtr<incompressible::RASModel> turbulence
(
    incompressible::RASModel::New(U, phi, laminarTransport)
);
and looking at the doc, I found that RASModel has no omega() method, while the kOmegaSST class which derives from RASModel has one.

I also found the declaration of New() which did not help me much:

Code:
//- Return a reference to the selected turbulence model
static autoPtr<RASModel> New
(
    const volVectorField& U,
    const surfaceScalarField& phi,
    transportModel& transport
);
I would like to know how can I access the method omega() corresponding to the turbulence model I am currently using.
What might help you is

mesh.lookupObject<volScalarField>("omega")

Have a look at Doxygen to find out what that actually does
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Old   October 19, 2009, 14:20
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John Deas
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Get it. Didn't know it could be that simple.

Thanks !
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Old   March 20, 2012, 06:59
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Arne Stahlmann
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Hi,

I have a question/problem accessing and modifying k and omega.
Using the above mentioned as simply taking
Quote:
volScalarField omega = mesh.lookupObject<volScalarField>("omega"); and e.g.
omega.boundaryField()[patchi] == 0.0;
does not change anything in my runs. I can access the omega field, but I cannot change it .

Any hints?
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Old   March 20, 2012, 08:40
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Bernhard Gschaider
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Quote:
Originally Posted by Arnoldinho View Post
Hi,

I have a question/problem accessing and modifying k and omega.
Using the above mentioned as simply taking
does not change anything in my runs. I can access the omega field, but I cannot change it .

Any hints?
You want a reference but you're creating a copy
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Old   March 20, 2012, 09:09
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Arne Stahlmann
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Hello Bernhard,

I'm sorry to say that I'm not that familiar with c++ and references/pointers. I tried to reference the object in the following ways:
Quote:
volScalarField &omega = mesh.lookupObject<volScalarField>("omega");
volScalarField const &omega = mesh.lookupObject<volScalarField>("omega");
In the first case, the compiler complains
Quote:
invalid initialization of reference of type ‘Foam::volScalarField&’ from expression of type ‘const Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>
whereas in the second case, I can't change the omega values (because of const).

I know that I definitely have to improve my c++ skills, but could you nevertheless give me the correct referencing syntax here?

Thanks,
Arne
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Old   March 20, 2012, 09:58
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Bernhard Gschaider
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Quote:
Originally Posted by Arnoldinho View Post
Hello Bernhard,

I'm sorry to say that I'm not that familiar with c++ and references/pointers. I tried to reference the object in the following ways:
In the first case, the compiler complains
whereas in the second case, I can't change the omega values (because of const).

I know that I definitely have to improve my c++ skills, but could you nevertheless give me the correct referencing syntax here?

Thanks,
Arne
Usually if you only get a const-reference it is because the designer of the class doesn't think it is a good idea. If you disagree google for const_cast

My last answer (about const_cast) was meant to be in answer of this message. I relocated it

Last edited by gschaider; March 20, 2012 at 10:56. Reason: Answered wrong message
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Old   March 20, 2012, 11:07
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Arne Stahlmann
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Thanks, I already got the casting working and am currently trying to understand a bit more about it - esp. the "unwanted behavior" of a const_cast.
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