New option to disable eddy currents in 3D conductive regions


A new option has been added for volume regions of type “Solid conductor” in 3D magnetic applications. This option allows considering only DC currents (i.e., by forcing Flux to disregard eddy currents). This DC component corresponds to the current density that would flow in the region with a frequency approaching 0 Hz.

In the dialog box of a volume region of type “Solid Conductor ”, there is a new checkbox for disabling the consideration of eddy currents during the solving process (“No eddy current option”), as shown in Figure 1:

Figure 1. Dialog box for creating a Solid Conductor volume region in Flux 3D, showing the new option for disabling the evaluation of eddy currents in the solving process.

Behavior of Solid Conductors regions with the new option

  • If the box is not checked, Flux takes eddy currents in account during the solution in this region. This is the usual case of solid conductors.
  • If the box is checked, Flux disregards eddy currents in the region during the solution and only DC currents are taken into account.

Availability in Flux 3D applications

This new feature is available for "Solid Conductor" volume regions in the following applications:

  • 3D steady state AC magnetic;
  • 3D transient magnetic and
  • 3D steady state AC magnetic application coupled with transient thermal application.
Note: One possible use of this new option is to simulate solid conductors fed by an external electrical circuit at zero frequency, since Flux doesn't support solid conductors nor circuit coupling in 3D magnetostatic applications. To do so (that is, to simulate solid conductors fed by an external electrical circuit in a magnetostatic or zero frequency condition), the user must:
  • define a 3D transient application;
  • create a scenario with two instants of time (i.e. two time steps), including the first one at t = 0 s;
  • set the “No eddy current option” in the volume regions of type “Solid conductor region”;
  • solve the scenario;
  • post-process the project at the second time step.


The “No eddy current option” is compatible with the “application” option ( in the “Formulation Model” tab) set to:
  • “Automatic formulations” or
  • “Magnetic scalar potential and electric vector potential formulations”.
For now, the “No eddy current option” has no effect with the option “Formulation Model” set to:
  • “Magnetic vector potential and electric scalar potential formulations”.
As a matter of fact, in this last case, even if the “No eddy current option” is set for a given volume region, Flux is still going to take eddy currents into account in that region.

Under such circumstances (that is, when the “No eddy current option” is set but is not compatible with the “Formulation Model” of the current application), a clear warning message is displayed to inform the user that the option is ineffective.