On 08/18/2016 09:39 AM, thomas stephens wrote:
id_X looks like this:
|
template<intspacedim>
classIdentity:publicFunction<spacedim>
{
public:
Identity():Function<spacedim>(){}
virtualvoidvector_value(constPoint<spacedim>&p,Vector<double>&value)const;
virtualdoublevalue(constPoint<spacedim>&p,constunsignedintcomponent
=0)const;
};
Identity<spacedim>id_X();
|
Do I need to implement nabla_X id_Xfrom W.'s expression (v_h,
k_{bar,h})_X = - (nabla_X v_h, nabla_X id_X)_X above, or is there a
way to convince dealii to do this for me?
You can interpolate this function onto a finite element function, and
then compute its gradient.
I suspect that it would be simpler to use the form of the surface
gradient that involves the normal vector. You know what
grad id_X
is (namely the identity matrix), from which you can compute
grad_X id_X
if you know the normal vector (which you should be able to get from X
somehow).
Best
W.
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www: http://www.math.colostate.edu/~bangerth/
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