k-Wave

1. magnus
   

   Member
   Joined: Oct '20
   Posts: 1

   Hi,

   I'm using pstdElastic2D for some simulations of a lamb wave propagating in a plate. I'm a bit puzzled by the effect of the 'PMLSize' input argument. If explicitly stated to a value eg 10, I do get a reasonable result. However, if I don't include this argument, I get a completely different behavior of the propagating lamb wave: higher propagation velocity and lower amplitudes (more damping with longer distance traveled.) According to the documentation, the default value of 'PMLSize' is also 10, so results should be identical. I have not found a way to read back the 'PMLSize' parameter so I'm not 100% sure what is actually used in the simulation if not stated explicitly.
   Is there a way to read back all the parameters used in the simulation?
   Is there any explanation for the behavior observed?

   Best regards
   Magnus

   Posted 1 month ago #

2. Andrea Addison
   

   Member
   Joined: Jan '20
   Posts: 7

   Hi,

   I want to add another question that I believe related to this topic.
   How we should decide the "PML_size" grid size in pstdElastic2D? In general, is 5 points per wavelength will be sufficient for full absorption in PML?

   Thank you for your time and effort,
   Andrea

   Posted 1 month ago #

3. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,390

   @Magnus: In 2D, the default size is 20 grid points. Worth checking that things you care about are not within the PML. There is no straightforward way to see the parameters, but you can see the defaults in /private/kspaceFirstOrder_setDefaults.

   @Andrea: 5 points seems a little slim to me. I normally use 10 as a minimum, preferably more. The performance depends on the frequency content relevant to the grid spacing, and also the angle of incidence. There are some details for the fluid code in this paper that might be interesting, as well as some plots in the k-Wave user manual.

   Brad

   Posted 6 days ago #

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