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Ansys Learning Forum › Forums › Discuss Simulation › Optics › FDTD:: simulation of directional coupler › Reply To: FDTD:: simulation of directional coupler

April 9, 2024 at 5:40 pm
Zhongdi Peng
Subscriber

Thanks Guilin for your suggestions, I have a few questions before further running a finer mesh simulation:

  1. Is the mesh size 0.07um also applicable to VarFDTD's dX/dY?
  2. I am using 'conformal variant 0' as mesh refinement in FDTD, where the mesh setting does not include any PML region. For better convergence, should I keep using that or use "conformal variant 1" instead? How can I check the mesh size in PML?
  3. A coarse mesh before PML requires less layer of PML for convergence, if I understand it correctly in your post: Reason for divergence and solution. In this case, I am afraid I had a bad PML absorption effect, where I can get 'standing wave' feature with 'Stabilize PML' setting. To further improve the absorption, is it possible to set a coarse mesh near PML region?
  4. In your forum post : Reason for divergence and solution, you have asked user to try with Metal boundary to check whether we should decrease step time dt. I tried Metal boundary (still with coarse mesh of (0.2,0.2,0.2) um) with same photonic structure and get similar 'standing wave' feature at the end (image attached). It was not diverged, which may due to the short running time. Based on this comparison result, should  change dt as well in my next simulation with finer mesh?

Best, Zhongdi