Symmtery Boundary Codnition

Hey Netgen/NGSolve community!

I have a quick question and I hope, the answer is also a quick and short one:
I want to minimize the necessary resources for the execution of my model by implementing a symmetry boundary condition and thus nearly halve the computing effort.

I know, it works with a Neumann BC but I don’t know how to implement it in my code.

Thanks for your help!

neumann bc is natural and you get it by default, so just solve the problem on the half domain
best, Christopher