Problem in the calculation of the normal gradient on a boundary face
 

Hi everyone,

I have a big problem with something a priori easy to calculate but in which I really don't succeed to do...

I want to calculate a heat flux in a flat plate (with a thickness) and so I calculate the gradient of the temperature (with GradientOfUnstucturedDataSet). In then take the component of the gradient which is normal to the face I want to have the heat flux.

In the solid, the values given are good (non zero) and equal to the theoretical values, ok...

But when I want to show the normal component of gradient on a boundary face by using ExtractBlock and then ExtractSurface, the values of the gradient are 0 everywhere... :( But in the volume it is still non zero !

I can add that I have tried to do some projection from the volume values to the boundary face by using "PointDataToCellData" and "Cell centers" but it doesn't work...

Do someone can help me about this? Is it a known bug ... ?
I'm using Paraview 3.14.1 64-bit on ubuntu 12.10, and I have also tried in Paraview 4.0 ...

Thank you so much !

Nicolas

up, I'm also interested in the answer
Thanks for your help

Cheers,
Francois