3D FDTD results not converged

xyjxyj1992xyjxyj1992 Member Posts: 5


I am working on the model verification, but the 3D FDTD results will not converge at the end of the simulation. I have tried finer meshing and longer simulation time, but none of them worked out. Besides, it seems that the autoshutoff level starts to increase at a certain point of the simulation time after I increase the simulation time. Does anyone have any suggestions? Thank you so much!

Currently the model only includes a semi-ring with the radius of 20um and two ports at the both end-faces of the semi-ring.


  • gsungsun Posts: 1,376Ansys Employee

    Hi, You used very high mesh accuracy, and it is a resonator instead of half-ring as you expected (you want to get the S parameters without reflection, I guess). To simulate such "half-ring", you will need to add straight waveguides at both ends, and they should be extended to the outside of PML. In addition, use higher mesh accuracy causes the PML total thickness smaller. Therefore, you will need to significantly increase the PML layers to keep its performance in good condition, eg, PML reflection is neglectable. Maybe using mesh accuracy 4 is enough. Please try.

  • xyjxyj1992xyjxyj1992 Posts: 21Member

    Thanks for your suggestions, I will try later!

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