In one wavelength how many mesh cells canbe possible in FDTD

Hi,
FDTD demands that a minimum of 10 cells should be there per wavelength due to stability reasons (32 or 64 bit will not matter here). The maximum number of cells per wavelength is upto you. But if you increase the no.of cells, the memory requiremnt will increase considerably and the time step size will decrease further so that the total simulation time will increase.
Considering the fact that a 32-bit system cannot address more than 4 GB of memory, it is not advisable to increase the number of cells beyond 20 or 30, but I think 12-15 cells will give good results. But if your problem size is small (in terms of wavelengths), then you can go for 20 or 30 cells per wavelength.
My advice is not to go beyond 20 cells per wavelength.

Best Regards
Jithesh

Hello,

Yes, Jithesh is correct...
But some comments...
1. Minimum Cells
You can use less than 10 cell per wavelength say 7 or 8 but you won't get accurate results & you may have stability problems even in comercial FDTD codes...

2. Maximum Cells
You can use more than 30 cells per wavlength say 40 or 50 but again here the time step will be reduced and convergence will take longer...& may be memory requirement problems may not be a issue with 64 bit OS with good RAM

3. Optimum No. of cells
To get desired results for a give problem in terms of lambda most of the FDTD codes or commercial packages will give good results around 15 to 20 cells per wavelength...

I hope this helps you...


---manju---