Differens between FIT and FEM

CSTs transient solver is based on Finite Integral Technique (FIT), and I know more or less how that work. But Comsol uses another technique called Finite Elements Method (FEM) . How does FEM works, and how accurate are FEM compared to FIT?

and also what technique does ansoft use in their HFSS?

I hope somebody can tell a bit about this.

Hi!

HFSS is also based on FEM. I believe COMSOL (FEMLAB) is a general physics program to solve differential equations. It's strength are that you can adapt the program to your special problem requirement. On the downside the code will not perform as well as specialized tools.

Tools like HFSS and CST are specialized on electromagnetics. The solver have been optimised to solve exactly this single problem. (with maybe some extensions in thermal simulations). Therefore the performance should be better in this single field of expertise.

In both methods FEM and FIT you can get accurate results. As a matter of fact, the Frequency Domain solver in CST and HFSS have (even if they come from different theories, FIT and FEM) many similarities.

- tetrahedral meshing
- second order elements
- ...

I'm not an expert in FEM algorithm but I'm sure someone can recommend some nice books on this topic.

F.