TMF effect

Any heater may treat as a direct one, then the heating power in Watt is prescribed. Or as an inductor for an inductive heating model. In this case the electric current in A and the frequency in Hz is prescribed.

Additionally the heater can be used not as a heat source or sink but for the representation of the phase shifted alternating fields in the facility. The superposition of the alternating fields with the phase difference produces the traveling magnetic field. In the traveling magnetic field the phase of the maximum field value travels in axial direction through the furnace. The traveling magnetic fields (TMF) can be applied to force the melt convection if the melt is electrically conducting. The TMF model in CrysMAS is used in order to compute the Lorentz force acting on the melt.

The melt convection in in the TMF field is considered not as back-coupled to the electromagnetic field. Therefore it is enough to compute the distribution of the Lorentz force in the melt only once and then proceed with the fluid dynamics in the melt.

Arbitrary many heaters can be used as careers of the TMF effect. For activation of the TMF effect first define the existing or new heater as a direct one and then check the button TMF effect in the Heaters dialog. If your heater is an inductive one, then no TMF model can be applied, the alternating electromagnetic field has everywhere the same phase and differs from the TMF formulation. The TMF model is an extension of the alternating field model (AMF) for phase shifted currents.

Definition of the Traveling Field Field model (TMF) using the TMF feature of the heater. 

Figure 41. Definition of the Traveling Field Field model (TMF) using the TMF feature of the heater.

The dialog fields phase shift and Current [A] appeare. Additionally the dialog field Frequency [Hz] is activated. The values of the phase shift and electric current flowing azimuthally through the cross-section of the heater region can be entered. The frequency of the electric current should be specified in the Frequency [Hz] too.

Press Apply or OK after all settings for all heaters are completed.

Note

The frequency of the electromagnetic field is the frequency of the electric current in the heaters with the TMF effect which are treated as inductors. This frequency should be the same for all inductors.

Note

The TMF heater can be used for the simultaneous treatment of the heating effect and driving of the electromagnetic convection. It can be used also only for consideration of the influence of the electromagnetic field on the melt movement. In this case use a virtual heater with the Fixed power option and zero Watt Joule power.