The orientation of the normal vector on an inner interface

Dear NGSolve developers,

I am not able to solve a transmission problem for the Laplace problem using the hybridized mixed method with static condensation. I wonder if the “element_boundary” method gives a normal vector with the same orientation from both sides of the interface.

Programming the same problem using the “skeleton” NGSolve style gives the right answer.

Best regards,



Hi Salim,

in an element-boundary integral, the normal vector is always pointing outside of the element.

The problem with your ‘wrong solution’ is that a discontinuous H(div) has no Trace anymore.

To build the right hand side with the jump1 - term, you can do element-boundary integrals everywhere, and multiply with a selection function set to 1 at the interface.


Dear Joachim,

Thank you very much for the quick answer and for providing a solution to my problem.