Skip to content

Coil Topology: Closed Coil

Use a closed coil when the conductor sits fully within the simulation domain. The conductor forms a continuous loop, and no electrical connections leave the modeled region. This is the typical case for stranded coils, windings, or solid conductors without external terminals.

This topology defines no ports. Instead, you must give:

  • A point inside the coil
  • A directional vector that defines the current flow direction

Notes:

  • The coil volume must form a closed, electrically connected region.
  • The coil faces are not boundary faces.
  • The current path is entirely closed inside the domain.
  • The magnetic field orientation follows the right-hand rule with respect to the chosen current direction.
  • Closed coils work with impressed current, voltage, or circuit-based excitations, depending on the formulation.

When to use this

  • Full-geometry transformer windings that close on themselves inside the air box.
  • Toroidal inductors and solenoids modelled in their entirety.
  • Wireless-power-transfer / inductive-charging coils where both the primary and the secondary loop are fully contained in the domain.
  • Search coils and pickup coils in NDT/EMC setups.

Example

Figure 1 shows a stranded or solid coil fully embedded in the computational domain. No conductors cross the outer boundary.

Closed coil fully inside the domain
Figure 1: Closed coil entirely contained in the simulation domain. No entry or exit ports are available.

Define a closed coil topology as follows. x, y, and z give a point inside the coil. dx, dy, and dz give the current-flow direction:

coil_topology = CoilTopologyClosed(
    x=1.0, y=0.5, z=0.5,
    dx=1.0, dy=0.0, dz=0.0
)