Ampère’s Law and Current Conservation
The Ampère’s Law and Current Conservation node adds Ampère’s law and the equation of continuity for the electric current. It provides an interface for defining the constitutive relations and their associated properties. There are two types of this feature available, Ampère’s Law and Current Conservation in Solids and Ampère’s Law and Current Conservation in Fluids. This distinction decides how materials behave and how material properties are interpreted when the mesh is deformed.
Ampère’s Law and Current Conservation in Solids applies to materials whose properties change as functions of material strain, material orientation, and other variables evaluated in a material reference configuration (material frame).
Ampère’s Law and Current Conservation in Fluids applies to materials whose properties are defined only as functions of the current local state at each point in the spatial frame, and for which no unique material reference configuration can be defined.
In COMSOL versions 6.2 and earlier, this Solids/Fluids distinction was controlled within the Ampère’s Law and Current Conservation node by specifying Solid/Nonsolid in the Material type setting.
These features can be overridden with an Ampère’s Law feature or a Coil feature, which are identical to the ones in the Magnetic Fields interface, removing the electric potential and the current conservation equation from the selected domains.
The Constitutive Relation Jc-E and Constitutive Relation B-H settings are the same as Ampère’s Law for the Magnetic Fields interface. The Constitutive Relation D-E settings are the same as for Current Conservation for the Electric Currents interface.