Re: Surface integration

[Konstantinos Poulios]

Dear Lorenzo,

This is the correct way of calculating such integrals both regarding the current and the integral of the multiplier (i.e. reaction force). Not sure why you get a NaN.

Look for example at line 220 of this indentation simulation:
https://git.savannah.nongnu.org/cgit/getfem.git/tree/contrib/continuum_mechanics/plasticity_finite_strain_linear_hardening_tension_3D.py

We do exactly the same for calculating the applied force.

Just FYI, you can just provide the relevant model to gf.asm_generic() instead of 'V', 1, mf, dataV.

Remark, for debugging purposes you can use the Print function in GWFL, try e.g.
'-sigma*Print(Grad_V).Normal

or

'-sigma*Print(Grad_V.Normal)'

to see the values of the respective quantities at each integration point.

Best regards

Kostas

On Thu, Oct 28, 2021 at 6:38 PM Lorenzo Ferro <lorenzo.iron@gmail.com> wrote:

Dear All,

I tried to calculate the electrical flow through a mesh region,

like \int_{\Gamma} F(x)\cdot n\ d\sigma.

After some trials I found a working way by means of "gf.asm_generic", see the code here below:

Electrical _current = gf.asm_generic(mim, 0, '-sigma*Grad_V.Normal', MeshRegion, 'V', 1, mf, dataV)

Question_1: is this method correct or is there any other way to perform this kind of calculation?

Then, since it is a calculation performed on a Dirichlet region, I wanted to do the same calculation integrating the Lagrange multiplier. I tried the same technique but the result of the integration is NaN, probably because the multiplier variable has less DOF than MeshFem.

Question_2: How can I perform this integration?

Thank you in advance.

Lorenzo