Free Space
For electromagnetic modeling, it is quite common for the fields to extend into the environment of the device in question. It is therefore important not only to model the device itself, but also its surroundings. Typically, this is done by adding a box or sphere around the device’s geometry.
The Free Space node is used to specify the physical conditions in close proximity to the device — typically in air or vacuum. It adds a Magnetic Flux Conservation governing equation using the Relative permeability constitutive relation with the permeability, μr, set to one.