16. INDUCTION_HEATING Namelist

This namelist specifies the parameters that manage the computation of Joule heat source for induction heating simulations. It is required whenever the PHYSICS namelist option induction_heating is enabled. The computation solves an auxiliary electromagnetics (EM) problem that simulates the eddy currents induced by an external low-frequency magnetic field. The EM field equations are solved on the tetrahedral mesh specified by the EM_MESH namelist, which is generally different than the mesh used for heat transfer. EM boundary conditions are defined using ELECTROMAGNETIC_BC namelists. A properly configured model will typically include a magnetic induction source boundary condition with an external field defined by the INDUCTION_SOURCE_FIELD namelist.

The time scale of the forced EM equations is assumed to be very short compared to the fundamental time scale of heat transfer (see the INDUCTION_SOURCE_FIELD namelist parameter frequency.) To avoid introducing this short time scale into heat transfer, the rapid temporal variation in the Joule heat is averaged over a period or cycle of the forcing. In effect, the EM field equations evolve on a distinct inner “fast” time that unfolds in an instant of the outer “slow” time of heat transfer.

Caution

The electromagnetic models assume SI units by default. In particular, the computed Joule heat is a power density, W/m³ in SI units. If you want to use a different system of units, you must assign appropriate values to the PHYSICAL_CONSTANTS namelist variables vacuum_permittivity (\(\epsilon_0\)) and vacuum_permeability (\(\mu_0\)).

16.1. Namelist Variables

use_fd_solver

Enabling this flag activates the frequency-domain solver, using the configuration specified by the FDME_SOLVER namelist. Otherwise the standard time-domain solver is used instead, using the configuration specified by the TDME_JOULE_SOLVER namelist. The frequency-domain solver should be considered experimental for this application.

Type:

logical

Default:

.false.

prop_change_threshold

This control determines, at each heat transfer time step, whether the Joule heat source is recomputed to account for temperature-dependent changes in the EM material properties. The source is recomputed whenever the maximum relative difference between the current properties and those from the previous computation exceeds this threshold value. Otherwise, the previously computed source is retained. When the properties are independent of temperature, the Joule heat source is only recomputed when the forcing function changes.

At each heat transfer time step, this control governs the recomputation of the Joule heat source based :Type: real :Default: 0.3 :Valid Values: > 0 :Notes: The electrical conductivity and magnetic susceptibility are the only properties whose changes are monitored. The electric susceptibility only enters the equations through the displacement current term, which is an exceedingly small perturbation in the quasi-magnetostatic regime, and has essentially no effect on the Joule heat.

For electric conductivity, only the conducting region (where the value is positive) is considered when computing the difference. An underlying assumption is that this region remains fixed throughout the simulation.

data_mapper_kind (experimental)

This specifies the tool used to map fields between the primary heat transfer mesh and the EM mesh. Select “portage” to use an experimental data mapper based on the Portage toolkit, https://laristra.github.io/portage. Otherwise, the standard mapping tool will be used by default.

Type:

string

Default:

“default”

Valid Values:

“default”, “portage”