Magnetic Fields (mf)
The model is solved everywhere except in the feed gap region. By keeping this void, its default boundary conditions support surface currents closing the current loop. In inductor modeling it is crucial to respect current conservation as this is a law of nature (Ampère’s law).
1
In the Model Builder click Magnetic Fields .
2
In the Settings window for Magnetic Fields, select Domains 1–8 and 10–14 only (all domains except 9). Or first click the Clear Selection button , then click the Paste Selection button  and enter 1–8, 10–14 in the Selection text field.
Free Space 1
The default feature is tailored for being used in free space. In frequency domain and transient modeling, stabilization conductivity may be required but not for stationary modeling.
1
In the Settings window for Free Space, locate the Stabilization section.
2
From the σstab list choose User Defined. In the associated text field, type 0[S/m].
Ampère’s Law in Solids 1
Additional features are added for solid domains, starting with the core.
1
In the Physics toolbar click Domains and choose Ampère’s Law in Solids .
2
In the Settings window for Ampère’s Law in Solids, under Domain Selection, choose Core from the Selection list.
Domain Coil 1
A dedicated feature is added for the solid copper winding of the inductor. This feature makes it easier to excite the model in various ways.
1
In the Physics toolbar click Domains and choose Domain Coil .
2
In the Settings window for Domain Coil, under Material Type, choose Solid.
3
In the Settings window for Domain Coil, under Domain Selection, choose Winding from the Selection list.
4
In the Model Builder, expand the Domain Coil 1 node.
5
Right-click the Geometry Analysis 1 subnode and choose Output . There is already a default Input node.
6
Click the Input 1  node.
7
In the Settings window for Input 1, click the Paste Selection button and enter 58 in the Selection text field.
8
Click OK.
9
Click the Output 1  node.
10
In the Settings window for Output 1, click the Paste Selection button and enter 79 in the Selection text field.
11
Click OK.
The Coil with default settings will treat it a s a solid conductor and apply a current of 1 A flowing from the input to the output.
The node sequence under Magnetic Fields should at this point match this figure.