Add surface_integrals option
Add option to specify surfaces for integral calculation (maybe with surface_integrals: [3000,3100]).
- I don't know exactly how to implement this nicely.
- Especially \int_\Gamma ((\sigma \cdot n) \cdot n) ds \neq \int_\Gamma ((\sigma \cdot n) \cdot e_1) ds with unit vector e_1. If that would be case, I would just calc all scalar fields in (n,t_1,t_2) coord system easiliy. But the problem is, that (n,t) might not be (x,y)-aligned...
🤔 - Maybe restrict it to the force in (x,y,z) first? (for which we have a well-defined expression...)
- Especially \int_\Gamma ((\sigma \cdot n) \cdot n) ds \neq \int_\Gamma ((\sigma \cdot n) \cdot e_1) ds with unit vector e_1. If that would be case, I would just calc all scalar fields in (n,t_1,t_2) coord system easiliy. But the problem is, that (n,t) might not be (x,y)-aligned...
- FEniCS can only integrate scalars.