fdtd matlab adi
for smruti:
thank you mr iyami,for ur valuable suggestion,i want to just know,what is the actual meaning of ADI-FDTD,i think u know this better,if possible please refer some site or book by which i clearify my doubt.
ADI = alternating direction implicit
in standard fdtd you get the equations:
E^{n+1} = c_1*E^n + c_2 DEL x H^n
H^{n+1} = ... E^n
which means you compute the new E-field from old E and H values.
That is to say the equation is explicit.
Now if (some) of the values on the right hand side were also step n+1
values then you can run into trouble because ADI would need to update
E before H and vice versa. The equations are implicit because you cannot
write down simple update equations. The only solution which remains is
to use matrices.
ADI is a clever way to mix explicit and implicit steps to
1) get unconditionally stability form the implicit equations and
2) rather nice (tridiagonal) matrices for the update step.
The one big problem (classical) ADI has is that at material interfaces bigger timesteps
can lead to pretty big errors
As for references: there is a section on ADI in Taflove. Also Namiki's papers which
somebody else posted a short while ago are pretty accessible I think
for confi999
This is for Iyami - what is your opinion about recent trend of researches on implicit FDTD (CN, LOD etc). Are they fit for real-life applications or what is their future? Thank you very much
I have not tried them yet. The vague impression I got is that
a) CN may have mostly solved the large error at material interfaces at larger time step so it is
definitely worthwhile investigating
b) LOD is just a more efficient way to compute ADI (I have not read any paper yet only abstracts).
So I would try CN before LOD but mostly the question is what model you have. If you have lots of
fine geometrical details then I would not use these methods. However if you have rather simple
models with large uniform regions then I would give them a try.
Are they fit for real-life applications
they probably are but the real difficulty is to determine whether they are appropriate for a
concrete model.