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Old   August 9, 2012, 17:00
Default Problem about fvm::grad
Haomin Yuan
Join Date: Jan 2012
Location: Madison, Wisconsin, USA
Posts: 57
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As you know, in OF, the gradient operator only has fvc type. But if we want to write a coupled algorithm, we have the make a fvm::grad function.

I have write fvmGrad.C file define the fvm::grad function. Since the gradient of a scalar field is a vector field. So the gradient matrix should actually be three different scalar matrix, returns each component separately by multiple p scalar field.

Now I have met two problems, first is about the initialization of the faceInterpolationScheme. Can some body give a example how to initial a faceInterpolationScheme?? I need this is because I need the weight to interpolation cell value to get face value.

The second problem is that when I initial the matrix coefficient like this
const vectorField& Sf = mesh.Sf();

const labelUList& owner = mesh.owner();

const scalar* lowerPtr = fvm.lower().begin();
const scalar* upperPtr = fvm.upper().begin();
const scalar* diagPtr = fvm.diag().begin();
scalar S;

S = Sf[facei].component(0) * weights[facei];
&lowerPtr[facei] = S;
&upperPtr[facei] = Sf[facei].component(0) - S;
The compilation of the finiteVolume is ok, but when I compile the solver that use fvm::grad(p), it returns the error
lvalue required as left operand of assignment
I do not know what this means.

Has anybody tried to do this before??

thank you in advance
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