Re: [Getfem-users] Export velocity gradient .vtk

[Eleonora Piersanti]

Hello!!

Since we are trying to validate the code, I need to compute the gradient of the velocity field to make some verifications.

I tried to compute the gradient directly with Paraview using the filter Gradient of Unstructured Data Set.

The problem is that with quadratic triangle this filter doesn't work properly. Then, someone from Paraview mailing list suggested me to use the filter Extract surface, that makes the triangles linear, and then the Gradient of Unstructured Data Set. In that way, I can compute the Gradient but I think that the accuracy is diminished. In fact, I do not obtain the result that I expect in my verifications. I do not understand if it is a problem of my code or a problem of accuracy of Paraview filter.

Thanks,

Eleonora

Il Domenica 1 Febbraio 2015 9:10, Michel Fournié <address@hidden> ha scritto:

Hello,

The gradient of 2D velocity field can’t be represented under vtk (it is not an export problem).

Generally from it you can compute the vorticity than can be plot.

M.F.

Le 1 févr. 2015 à 09:56, Eleonora Piersanti <address@hidden> a écrit :

Hi to everyone!

I computed a 2D velocity field U based on P2 elements. I computed its gradient with the function:

getfem::compute_gradient(mf1, mf2, U, V),

where mf1 is P2 element, mf2 is P1 element, U is the velocity vector and V is the vector containing the gradient which dimensions are 2*mf2.nb_dof() as prescribed by the userguide.

It seems to work.

Now, I would export the gradient field in .vtk. How can I do?

Thank you,

Nora

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