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-   -   nAlphaCorr and nAlphaSubCycles (http://www.cfd-online.com/Forums/openfoam-programming-development/70534-nalphacorr-nalphasubcycles.html)

santiagomarquezd November 26, 2009 18:20

nAlphaCorr and nAlphaSubCycles
 
Hi all FOAMers, I'm preparing a document about scalarTransportFoam, icoFoam and interFoam (coming soon) and can't figure the necessity and differences between nAlphaCorr and nAlphaSubCycles in interFoam code, What are each one for?

Regards.

LarsPT October 6, 2010 17:49

Hi Santiago,

although it is an old thread, have you find out the difference, yet? I'm using OF-1.6 and had a look at the alphaEqnSubCycle.H file. There nAlphaCorr is just read but never used.

Thanks!

Lars

santiagomarquezd October 6, 2010 18:18

Lars, subCycling is explained in Berberovic's paper, basically actual temporal step is subdivided n times, then advective equation for alpha is integrated these n times and then divided by the hole timestep, is a kind of temporal filtering in order to improve stability.
As regards alpha corrections, they are used in a fixed point iteration over alpha to improve the quality of solution. Respect of this, I haven't done too much research in the convergence of this iteration, etc.

Regards.

LarsPT October 6, 2010 19:51

Thank you! I knew about the subCycling but I was wondering whether there is some important meaning of the correctors. I have the paper, so I'll check it again.

Kind regards,

Lars

mohsenkh599 October 12, 2010 08:31

compiling error
 
Hi every body,
I have a problem when I want to compile a model.
the error is:

************************************************** *********************
************************************************** *********************

viscoelasticLaws/mohsen/mohsen.C:159: error: no match for ‘operator==’ in ‘Foam::operator+(const Foam::tmp<Foam::fvMatrix<Type> >&, const Foam::tmp<Foam::fvMatrix<Type> >&) [with Type = Foam::SymmTensor<double>](((const Foam::tmp<Foam::fvMatrix<Foam::SymmTensor<double> > >&)((const Foam::tmp<Foam::fvMatrix<Foam::SymmTensor<double> > >*)(& Foam::fvm::div(const Foam::surfaceScalarField&, Foam::GeometricField<Type, Foam::fvPatchField, Foam::volMesh>&) [with Type = Foam::SymmTensor<double>](((Foam::GeometricField<Foam::SymmTensor<double>, Foam::fvPatchField, Foam::volMesh>&)(&((Foam::mohsen*)this)->Foam::mohsen::a_))))))) == Foam::operator+(const Foam::tmp<Foam::GeometricField<TypeR, PatchField, GeoMesh> >&, const Foam::tmp<Foam::GeometricField<Type1, PatchField, GeoMesh> >&) [with Type1 = Foam::Tensor<double>, Type2 = Foam::SymmTensor<double>, PatchField = Foam::fvPatchField, GeoMesh = Foam::volMesh](((const Foam::tmp<Foam::GeometricField<Foam::SymmTensor<do uble>, Foam::fvPatchField, Foam::volMesh> >&)((const Foam::tmp<Foam::GeometricField<Foam::SymmTensor<do uble>, Foam::fvPatchField, Foam::volMesh> >*)(& Foam::operator*(const Foam::dimensioned<double>&, const Foam::tmp<Foam::GeometricField<Type, PatchField, GeoMesh> >&) [with Type = Foam::SymmTensor<double>, PatchField = Foam::fvPatchField, GeoMesh = Foam::volMesh](((const Foam::tmp<Foam::GeometricField<Foam::SymmTensor<do uble>, Foam::fvPatchField, Foam::volMesh> >&)((const Foam::tmp<Foam::GeometricField<Foam::SymmTensor<do uble>, Foam::fvPatchField, Foam::volMesh> >*)(& Foam::operator&(const Foam::tmp<Foam::GeometricField<TypeR, PatchField, GeoMesh> >&, const Foam::tmp<Foam::GeometricField<Type1, PatchField, GeoMesh> >&) [with Type1 = Foam::SymmTensor<double>, Type2 = Foam::SymmTensor<double>, PatchField = Foam::fvPatchField, GeoMesh = Foam::volMesh](((const Foam::tmp<Foam::GeometricField<Foam::SymmTensor<do uble>, Foam::fvPatchField, Foam::volMesh> >&)((const Foam::tmp<Foam::GeometricField<Foam::SymmTensor<do uble>, Foam::fvPatchField, Foam::volMesh> >*)(& Foam::operator-(const Foam::dimensioned<Type>&, const Foam::tmp<Foam::GeometricField<Type1, PatchField, GeoMesh> >&) [with Form = Foam::SymmTensor<double>, Type = Foam::SymmTensor<double>, PatchField = Foam::fvPatchField, GeoMesh = Foam::volMesh](((const Foam::tmp<Foam::GeometricField<Foam::SymmTensor<do uble>, Foam::fvPatchField, Foam::volMesh> >&)((const Foam::tmp<Foam::GeometricField<Foam::SymmTensor<do uble>, Foam::fvPatchField, Foam::volMesh> >*)(& Foam::operator*(const Foam::scalar&, const Foam::GeometricField<Type, PatchField, GeoMesh>&) [with Type = Foam::SymmTensor<double>, PatchField = Foam::fvPatchField, GeoMesh = Foam::volMesh](((const Foam::GeometricField<Foam::SymmTensor<double>, Foam::fvPatchField, Foam::volMesh>&)((const Foam::GeometricField<Foam::SymmTensor<double>, Foam::fvPatchField, Foam::volMesh>*)(&((Foam::mohsen*)this)->Foam::mohsen::a_))))))))))))))))))))’

************************************************** ************
************************************************** ************

and the model is :

// Velocity gradient tensor
volTensorField L = fvc::grad( U() );

// Convected derivate term
// volTensorField C = tau_ & L;

// vorticity term
volTensorField Vor = L - L.T();

// Twice the rate of deformation tensor
volSymmTensorField twoD = twoSymm( L );


// fc
scalar fc = 0.5; //1 - 27 * det( a_ );

//double dot term

// volSymmTensorField mk = -( (2 / 35) * ( 1 - fc ) * twoD - (2 / 7) * ( a_ & twoD + twoD & a_ + (1 / 2) * tr( twoD & a_ ) * I_ ) - fc * tr( twoD & a_ ) * a_ );

// Stress transport equation
tmp<fvSymmTensorMatrix> aEqn
(
fvm::ddt(a_)
+ fvm::div(phi(), a_)
==
( 1 / 2 ) * ( Vor & a_ - a_ & Vor ) + ( 1 / 2 ) * keisi_ * ( twoD & a_ + a_ & twoD + 2 * ( ( (2 / 35) * ( 1 - fc ) * twoD - (2 / 7) * ( 1 - fc ) * ( a_ & twoD + twoD & a_ + (1 / 2) * tr( twoD & a_ ) * I_ ) - fc * tr( twoD & a_ ) * a_ ) ) + 2 * ci_ * twoD & ( I_ - 3 * a_ )
//+ twoSymm( C )
//- zeta_ / 2 * ( (tau_ & twoD) + (twoD & tau_) )
//- fvm::Sp( epsilon_ / etaP_ * tr(tau_) + 1/lambda_, tau_ )
);

aEqn().relax();
solve(aEqn);
// Viscoelastic stress
tau_ = (etaP_ / keisi_) * (a_ - I_);
}

************************************************** ****************
************************************************** ****************

where "a" , "tau" and "I" are symmetric tensors and "Vor" is asymmetric tensor. and the others are constant parameters.

best


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