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FDTD vs. FEM --Which one is better?

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Amit_1

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Hi everyone,

Out of FDTD technique and FEM technique, which one is better and why?
Isn't FDTD better than FEM ?

Thanks.
 

Hi,
FDTD is for time varying field and FEM is for harmonic field (time is frozen).
FDTD is rather for CEM for example.
FEM work well for antennas.
About computer memory, the two simulations are volumic meshes so need huge memory (depend on the structure simulated).

Regards
 

Hi everyone,

Out of FDTD technique and FEM technique, which one is better and why?
Isn't FDTD better than FEM ?

Thanks.

15 years ago, computers used to have a small amount of memory say 1-2GB and FEM uses more RAm so it could be a pb on large model .

It depends on your application but most application I am familiar with such as antennas, microwave components, Fem beats fdtd.
 

For commercial EM solvers, I would say FEM is the most popular. Ansys HFSS and Maxwell are FEM, CST is FEM and a bit of MoM from what I've read (Method of Moments). ADS Momenta uses MoM. I know Sim4life, a medical EM software suite, uses FDTD method.

FEM can certainly solve in the time domain as well. I'm not really well enough versed to know when a FEM method becomes less/more efficient than a FDTD method in terms of parallelization and RAM. But if you are ever using a commercial solver, you are probably using FEM. I have taken a Computational EM class and I can tell you I find FDTD much more intuitive. As such its probably more popular for those making custom codes. Fortunately we live in a day where commercial EM solvers are very powerful and flexible, slowly removing the need for custom EM solver.
 

FEM can certainly solve in the time domain as well

With the FEMM42 tool, it is possible to make simulations in time domain by using the LUA script.
 

The answer to this question depends on to a great extent on the particular design problem that is to be analyzed. There are various EM simulation tools based on different numerical techniques. Solver for a particular design can be selected based on type and size of the design. Choosing the right technique for solving a design problem is important, as choosing the wrong one can either result in incorrect results, or results which take excessively long to compute.

Finite Element (FEM) and Finite Difference Time Domain (FDTD) solutions are used almost in all commercial software. Although in principal these two technologies could be used to solve the same problems there are often good practical reasons why one particular simulator is better suited to solving a particular problem type.

There are many considerations to take into account when assessing the suitability of a particular EM analysis tool for design. Applications better suited to FDTD simulation include a very large problem with a limited number or Ports likes of antenna placement on vehicles/aircraft and the analysis of antenna performance in the presence of detailed human body models. While FEM is suitable for geometry less than 10 times wavelength. FEM is fast compare to FDTD for simulation with a large number of ports.
 

Hi everyone,

Out of FDTD technique and FEM technique, which one is better and why?
Isn't FDTD better than FEM ?

Thanks.

Each of the computational techniques have advantages and bottlenecks.. Completely depends on application, type of simulation (time/frequency- wideband, narrowband), type of problem (scattering, radiation, complex dielectric etc.), solution time and memory requirements etc. There is no method which is better than the other in all aspects.
 

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