Domain Decomposition and fem variables

General Discussion
1

In the example about Domain Decomposition, for the “Schwarz non overlapping Scheme”, lambda is actualized as: lambda = lambda - (u-U)/2

What I don’t really understand is that U is a fem variable defined inside a mostly circular domain cut by a inclined line, and u is a fem variable defined inside rectangular domain with an inclined side that coincides with that one of the circular domain.

So, what does U-u mean? Those variables are defined over different domains that have a common boundary. So, in general, what do operate mixing variables of different domains mean?

Thanks,
Lluis

2

This depend strongly of the definition of lambda, here lambda is defined on the intersection of the two domain so no problem.