Open Boundary tool demonstration

For open or semi-open boundary problems, such as air-cored coils in free space, the objective is to reduce the solution domain area so that the boundary does not have an impact on the field solution.

There is a way, however, of reducing the solution domain without having to add a boundary that is some distance from the objects we wish to model. The method we are referring to is the Kelvin transformation. With the Kelvin transformation method, the boundary can be placed quite close to the objects we wish to model and can easily be automated. The Open Boundary tool, created by Infolytica for use in MagNet, ThermNet, or ElecNet, addresses this very issue. It is offered as a Free Add-on and can be downloaded here. After a user has installed the executable, an additional menu item (Open Boundary) is made available under the 'Boundary' menu. To use the tool, you simply select the Open Boundary menu option after the model has been completed. As an aside, using the Open Boundary tool eliminates the need to create air boxes around the objects you wish to analyze.

In the illustration above, we show the objects that form the model for this example. The model consists of two coils and a steel plate.

Results

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The model, without and with the open boundary -- The Open Boundary tool determines the overall dimensions of the device to be analyzed, computes the radius of the circumcircle, and then creates the boundary around the model based on those calculations. The results of the Kelvin transformation, which transforms all the space external to the boundary into the space inside a circular region, is represented by the small circle in the top right hand side of the illustration.

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The resulting flux plot for the model, without and with the open boundary. As you can see, the Open Boundary tool provides excellent results.

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The same flux plot of the model, as above, without and with the open boundary, except that the contours are colored.