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Coil Direction

Vector field giving the unit local conductor direction \(\boldsymbol{\hat{\tau}}\) inside every cell that belongs to an excitation coil. It is the dimensionless direction in which positive coil current would flow at that point.

Registered name: "Coil Direction".

Cells outside every coil evaluate to \((\mathrm{NaN}, \mathrm{NaN}, \mathrm{NaN})\), so coil paths stand out visually against the surrounding mesh in ParaView without a threshold filter.

Reverse-direction marker

Cells covered by the optional reverse_direction marker of a CoilSpecification carry a flipped \(\boldsymbol{\hat{\tau}}\), so this coefficient already reflects the go-side / return-side sign of a series winding without further bookkeeping.

Typical use

  • Visualising the current path inside a closed coil or a regex-marker spec that spans several disjoint pieces.
  • Defining custom integrands such as \(\mathbf{A}\cdot\boldsymbol{\hat{\tau}}\) via CffExpressionVector / CffExpressionScalar.