volSymmTensorFields Magnitude

ParaView Support
1

Hi
I found that Paraview calculates a volSymmTensorFields Magnitude via the following relation:

tau_tot = (tau_xx^2 + tau_yy^2 + tau_zz^2 + tau_xy^2 + tau_xz^2 + tau_yz^2)^0.5

However, we know that the correct form of that is:

tau_tot = (tau_xx^2 + tau_yy^2 + tau_zz^2 + 2*tau_xy^2 + 2*tau_xz^2 + 2*tau_yz^2)^0.5

To check you can set the initial values of a volSymmTensorFields as (1 1 1 1 1 1). the mag of this tensor is 3. Now see its magnitude in paraview. You will see that it gives 2.45, not 3!
Could you please explain the reason?

2

Which filter compute this volSymmTensorFields ?

3

Actually, I computed volSymmTensorFields in OpenFOAM and I just wanted to see the results in paraView.

4

ParaView compute the magnitude of any n-component array using the same formula, there is no specific case for symmetric tensors I’m afraid.

You can compute anything you want using the calculator though.

5

Yes. I think this is from OpenFOAM nad is not related to paraView.