Dear David,
If you use C++, here is some sample code that could help you:
getfem::ga_workspace workspace(md);
workspace.add_expression("1", mim, B_BOUNDARY, 0);
workspace.assembly(0);
scalar_type area = workspace.assembled_potential();
workspace.clear_expressions();
workspace.add_expression("u(1)", mim, B_BOUNDARY, 0);
workspace.assembly(0);
scalar_type dx = workspace.assembled_potential()/area;
This snippet finds the displacement dx of the centroid of a mesh region
B_BOUNDARY due to a displacement field u.
Best regards
Kostas
On Thu, Apr 26, 2018 at 10:03 AM, David Danan <[email protected]>
wrote:
> Dear GetFEM++ users,
>
> i was wondering whether it was possible to define a scalar variable
> computed over a surface, namely in my case a volume bounded by surfaces.
>
> That is to say, something along the lines of
> Volume= (1/3) int_{Gamma} Det(Grad_u+Id(3)) Normal.Inv(Grad_u+Id(3)).(X+u)
> dGamma
> where we denote by:
> -Gamma, the surfaces in the undeformed configuration
> -u, the displacement field
> -X, the position in the undeformed configuration
>
> Also, out of curiosity, is it possible to compute such a thing in
> post-processing?
>
> Thanks in advance,
> David.
>
