29  Domains

The domain Ω in which we seek the solution to the Poisson equation, consists of n subdomains Ωi, where the union of the subdomains is

Ω=Ω1Ω2Ωn

and the intersection of two subdomains is always

ΩiΩk=,ik.

Across the individual Ωi the physical parameters, e.g., conductivity, density, are usually constant.