Mutual inductance*
Mutual inductance is the inductive coupling between two conductors or windings, where current in one produces magnetic flux linked with the other. It depends on geometry of the conductors, distance between them, and magnetic properties of surrounding materials.
Mutual inductance is important for analysis of transformers, coupled coils, transmission lines, busbars, cable conductors.
In QuickField, mutual inductance can be analysed using DC Magnetics, AC Magnetics or Transient Magnetics.
References
Wikipedia: Mutual inductance
All About Circuits: Mutual inductance and basic operation
QuickField examples
Transmission line inductance matrix