# Non-meshed coil: about

## Definition

A non-meshed coil is a geometric entity of circular, rectangular or more complex shape, which superposes to the mesh and is independent from it.

The computation of the magnetic field created by the distribution of current is then carried out using the Biot and Savart formula in an analytic or semi-analytic way. (See § Non-meshed coils (3D))

## Geometrical aspect

A non-meshed coil is not a part of the geometry, i.e. it is not formed of points, lines, faces and volumes. Therefore, it will not be taken into account by the geometric construction and the mesh generator. You can describe it before or after generating the mesh.

## Physical aspect

A non-meshed coil is always associated to an electric component (of stranded coil conductor type). The value of the current in a wire of the coil is that defined via this component.

The two possible situations are presented in the table below.

If the component is … | the value of the current is … |
---|---|

independent (not a part of an electric circuit) |
set by the user |

dependent (belonging to an electric circuit) |
set by the circuit |

Reminder: the circuit coupling is carried out with the Transient Magnetic and Steady state AC Magnetic applications.

## Symmetries and periodicities

If the coils are entirely located in the study domain, Flux automatically creates the symmetrical and/or periodic coils according to the conditions of symmetries and/or periodicities imposed in the study domain. We speak then about duplication of the coils.

The “original” coils and the “copies by duplication” can be connected in series or in parallel.

The user can deactivate the command of coil duplication.

## Different types of coils

The different types of coils in Flux are:

- basic coils: of circular or rectangular shape
- composed coils: the shape is defined by the user (path composed by successive points)
- coils for rotating machine applications: saddle coil or multi-saddle coil

## Geometric description

To understand the description of the coils in Flux, it is necessary to define the concepts of mean fiber and section (see figure below).

The mean fiber is the line that defines the shape of the coil.

The section is the surface of the coil perpendicular to the mean fiber.

The mean fiber passes by the center of gravity of the section.