The Divergence Constraint subnode is available from the context menu (right-click the Wave Equation, Electric parent node) or from the Physics toolbar, Attributes menu. It is used for numerical stabilization when the frequency is low enough for the total electric current density related term in the wave equation to become numerically insignificant. For The Electromagnetic Waves, Frequency Domain Interface and Heat Transfer Interfaces the divergence condition is given by

and for The Electromagnetic Waves, Transient Interface it is

Enter a value or expression for the Divergence condition variable scaling ψ0.

For the Electromagnetic Waves, Frequency Domain and Microwave Heating interfaces, the SI unit is kg/(m⋅s3⋅A)). The default is 1 kg/(m⋅s3⋅A).