k-Wave

1. chuck_c
   

   Member
   Joined: Oct '13
   Posts: 4

   Hi,

   I am trying to simulate a scenario using a GPU but the space is too large for my GPU's memory. The scenario is a spherically focused ultrasound transducer with a large amount of water stand-off, so I think the propagation from the transducer face through the initial water section should be quite similar regardless of my imaging target. I was wondering whether it would be possible to simulate the transducer one time and then use the output from that as input into the smaller target space. I am open to other solutions to this problem but this seemed intuitive.

   Thanks for the nice simulation package.

   -Charles

   Posted 11 years ago #

2. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,643

   Hi Charles,

   One possibility would be to setup a simulation just containing the transducer in water, and record the time varying pressure over a 2D plane on one side of the domain, say the right. In a new simulation containing your imaging target, you could then enforce this pre-recorded pressure over an identical 2D plane as a Dirichlet boundary condition on the left of the domain. This should give you the same acoustic field as if you had performed one larger simulation (keeping in mind the time-staggering between inputs and outputs as described in the k-Wave manual).

   Do you want to measure the reflected sound back at the transducer surface, or just look at the scattered waves around your imaging target? Also, are you using a CW or pulsed source?

   Brad.

   Posted 11 years ago #

3. chuck_c
   

   Member
   Joined: Oct '13
   Posts: 4

   Thank you for the reply. I think this should help me get started. I would possibly like to measure the sound reflected back at some point, but I will try to focus on one thing at a time! It seems the reverse of your suggestion (ie. propagate back via a plane on the left side of the second space into the first space) might be a possible solution. Also, I am using a ~10 msec pulse, so I think it can be viewed as somewhat continuous.

   Posted 11 years ago #

4. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,643

   Hi Charles,

   For a CW source, I think the situation is slightly more complicated. If you have a homogeneous medium, when you enforce the source in your second simulation as a Dirichlet boundary condition, the resulting wavefield downstream from the 2D plane will be the same as if you had run one big simulation.

   However, in a heterogeneous medium, the waves scattered from your imaging target will then also be reflected from the source plane over which the Dirichlet boundary condition is being applied. This is easiest to imagine in the case of the source pressure being zero. This will result in a pressure of zero being enforced across the 2D plane, which will reflect the sound waves.

   You could avoid this by using a source signal that has finished being transmitted before any reflections reach the source plane.

   Brad.

   Posted 11 years ago #

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