[dune-fem] Flux/Source terms in DgPrimalMatrixAssembly (Dune-FEM-DG)

[Tobias Malkmus]

Hi Amal,

This information is contained in a so-called EvaluationContext, namely:
local

Here the quadrature point, u evalutate at the quadrature point and the
gradient of u at the quadrature point is stored in.

How this is accessed is best explained if you have a look at lines 273 -
279 in the file dune/fem-dg/operator/dg/discretemodelcommon.hh

Best Tobias


On 08/10/2017 07:08 PM, Sahai, Amal wrote:
> Hello
> 
> I have a question regarding the DgPrimalMatrixAssembly class from the DUNE-FEM-DG module. The code snippet I am interested in is from DgPrimalMatrixAssembly.assemble() in assemble/primalmatrix.hh:
> 
>             RangeType aphi(0);
>             if ( model_.hasStiffSource() )
>             {
>               model_.stiffSource( local, phi[localCol], dphi[localCol], aphi );
>             }
>             if ( model_.hasNonStiffSource() )
>             {
>               RangeType sNonStiff (0);
>               model_.nonStiffSource( local, phi[localCol], dphi[localCol], sNonStiff );
>               aphi += sNonStiff;
>             }
>             // subtract affine part and move to left hand side
>             aphi -= arhs;
>             aphi *= -1;
> 
>             JacobianRangeType adphi;
>             model_.diffusion( local, phi[localCol], dphi[localCol], adphi);
> 
>             JacobianRangeType bphi;
>             model_.advection( local, phi[localCol], dphi[localCol], bphi);
> 
> Am I correct in assuming that the function call to compute the source / flux terms by the model only passes the values (and gradients) of the basis functions? If so, do these calculations not require the actual reconstructed solution (using the values from the DOFs)? I am unable to understand how these values  are being accessed by the model class.
> 
> Regards
> Amal
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> 


-- 
Tobias Malkmus                 <tomalk at mathematik.uni-freiburg.de>

Mathematisches Institut               Tel: +49 761 203 5588
Abt. für Angewandte Mathematik        Universität Freiburg
Eckerstr. 1
79104 Freiburg


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