Guilin Sun
Ansys Employee

Please note that, periodic BC and PML BC mean they are for different structures. The former means infinite structure with repeated elements, and the latter is isolated, single element. It is not a surprise that they do not show the same characteristics.

I believe to understand the result physically can lead to a paper published to benefit others.


The size of the element also matters, to some extent. You can try very shallow or very deep (thickness), and see what happens.