In 3D models, it is possible to perform an automatic analysis of the geometry of a Coil to determine the local direction of the current flow in the domain given the input and output boundaries of the coil (or an interior boundary in the case of closed-loop coils). The analysis is performed in a dedicated study step,
Coil Geometry Analysis, which is typically solved before the main study step.
The study step can be used to compute both the current flow when using the Single conductor model and the direction of the wires when using the
Homogenized multiturn model.
In the case of a Single conductor coil, the study step solves a simple current conservation problem to determine the flow of a current applied to the metallic domain.
In the case of a Homogenized multiturn coil, the feature computes a vector field
e which represents the local wire density in the coil, as well as the length and average cross-section of the wires. The vector variable
eCoil can be plotted (for example, in a
Streamline or
Arrow Volume plot) to visualize the computed direction of the wires.
The Coil Geometry Analysis replaces the
Coil Current Calculation functionality available in previous versions of COMSOL Multiphysics. The new formulation is more robust and has a larger applicability than the previous one, as well as a number of improvements, such as support for solving multiple coils at once or for coils with nonconstant cross section. When opening a model saved in an older version of COMSOL Multiphysics, the Coil Current Calculation study steps are transparently updated to use the new formulation. It may however be necessary to regenerate the default solvers before proceeding with the solution.