k-Wave

1. Inge
   

   Member
   Joined: Sep '21
   Posts: 2

   Dear K-wave toolbox users and admins,

   At the moment I am working on a project in which I want to reproduce the study by Cox and Beard (2009) on Photoacoustic tomography with a single detector in a reverberant cavity. I am particularly interested in the Modal Reconstruction method.

   The coding can be split in two parts, first the simulation part and second the reconstruction part. As a first check I want to compare my simulated photoacoustic time series with the first part of a photo acoustic time series from a single source as presented in the study (fig 5). To do this I have simulated a rectangular reverberant cavity by defining a 3 cm thick metal box as the walls of my cavity. What I find is that acoustic pressure of my time series does decrease over time, while the time series presented in the paper does not. This is explained by the fact that they build a simulation assuming a reflection coefficient of 1, while in my case some of the acoustic pressure will propagate though the metal box and end up in the perfect matched layer.

   Does anyone have an idea how to to model a reflection coefficient of 1 using the K-wave toolbox? Or will this inherently be impossible because of how the toolbox is build? And if so, what direction would you suggest me to investigate?

   Thank you very much for your help!

   Inge

   Posted 2 years ago #

2. bencox
   

   Developer
   Joined: Mar '10
   Posts: 285

   Hi Inge,

   The trick has two parts. First take the initial pressure distribution on the grid that you wish to simulate. Expand it by flipping copies of it about the right-hand side and the top side (say). You will then have a domain that is twice as large in each direction, and has four copies of the original initial pressure distribution. Second, use periodic boundary conditions on the boundaries of that larger domain. The combination of these two will simulate all the reflections in the original (smaller) domain.

   Probably the easiest way to do this (and what I think we did in that paper) is to use the function kspaceSecondOrder, which has periodic boundaries by default.

   Hope that helps.

   Best wishes
   Ben

   Posted 2 years ago #

3. Inge
   

   Member
   Joined: Sep '21
   Posts: 2

   Dear Ben,

   Thank you very much for your response and helpful suggestions! I really appreciate it. I will implement the reflectivity with your tricks.

   Regards,

   Inge

   Posted 2 years ago #

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