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Coil Direction

Vector field that gives 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 under the optional reverse_direction marker of a CoilSpecification carry a flipped \(\boldsymbol{\hat{\tau}}\). So this coefficient already shows the go-side and return-side sign of a series winding. You do not need further bookkeeping.

Typical use

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