Field sources in DC conduction
With the problems of DC conduction, the field sources are external currents supplied to the boundary of a conductor. QuickField provides possibility to specify external current density at the edges or at the individual vertices of the model.
The current density specified at a point of the xy-plane corresponds to a knife-edge current collector, which is perpendicular to the plane of the model, and is described by the linear current density.
In axisymmetric case the vertex source represents a circular collector around the axis of symmetry or a point collector located on the axis. To incorporate both these cases, a total current value is associated with the vertex.
For the circular knife-edge collector the total current value is connected with its linear density by the relationship
I = 2πrσ.
Edge-bound current density in the plane of model represents a surface-bound external current density in three-dimensional world. It is specified by the Neumann boundary condition for the edge.