Fixing CAD geometries for FEM #2

We want to share an interesting observation with you.

As you may be aware, FEM allows the analysis of components with complex geometries. However, we've noticed a trend among users with little or without simulation experience. They attempt to load geometry files intended for production or aesthetic visualizations.

Creating efficient CAD models for FEM simulations is not about crafting the most intricate and visually appealing designs. FEM is a computationally intensive method that necessitates meaningful and functional geometries. In this context, the principle “less is more” applies, emphasizing the importance of focusing on essential details and optimizing geometries for accurate and efficient simulations.

Main principles

To create a straightforward and problem-free geometry for your simulation, consider the following key aspects for an optimal, simulation-friendly CAD file:

1. Create a single solid geometry for every separate conductor: In many CAD software programs, building the coil geometry from combined blocks is common to form a complete model. When creating geometry for simulation, these blocks should be fused to form a single solid. This helps remove unnecessary faces between blocks and simplifies geometric property setup and meshing. Coil turns that are not geometrically connected do not need to be fused but can be grouped into one partition to allow easier manipulation with the entire group.
2. Simplify geometry: Computer simulations use numerical models based on a limited set of physical equations. Physical effects that are less relevant are neglected and in a similar way, you should disregard specific geometrical details that have minimal impact on the result.

The most common pitfalls and their solutions

The following features can be removed or have to be fixed, as they consume a significant amount of computation time and resources without contributing considerably to the results.

Delete unnecessary elements and eliminate small details

In many cases, elements such as holding parts, dielectric tapes, and connections can be removed from the model. Small details have a negligible impact on simulation results. Still, they consume a lot of computation time, which needs to be resolved through meshing, significantly increasing the mesh element count.

Remove details such as small holes (fill in with the material) and gaps (use virtual gap model for core). Parts irrelevant to electromagnetics or heat removal from the core and windings can also be removed since heat transfer can be approximated using convective heat transfer boundary conditions.

Resolve inaccurately connected geometrical parts

Be cautious when connecting different parts during geometry creation. Faulty connections can result in meshing problems and calculation errors. Ensure that there are no overlaps or gaps between parts.

Ensure continuity in the magnetic component geometry

If your magnetic component features a specific channel or path, ensure it is continuous throughout the entire length to avoid meshing problems.

The final remark

By following these tips for creating optimal CAD models, you will achieve a geometry easy to manipulate, mesh, and compute efficiently.

If you encounter any other issues that require assistance navigating the nuances of geometry files, please don't hesitate to reach out. We're here to help ensure your simulation experience is efficient and rewarding.