Hi. I have a transducer which bounces sound off an object and then receives that sound.
I gather there is no nice way to set the object to "hard"; setting its properties to some large value like steel will make the Fourier solver unhappy.
I'm not ready to mess with the solver code, as mentioned in one post, to reset p or u at some grid locations (i.e. the object) to zero after each program iteration.
Could I do the following?:
Set source.u_mode to "dirichlet". Define source points to have an input signal velocity, and define object points to have u=0. Now, calculate p at my transducer points. The velocity there with be zero, as dictated by the Dirichlet b.c., but the pressure would be finite (and perhaps be multiplied by 2, since the transducer is now "hard" by virtue of u=0).
k-Wave
A MATLAB toolbox for the time-domain
simulation of acoustic wave fields
Using transducer as both source and receiver, with reflector as well.
(4 posts) (2 voices)-
Posted 6 years ago #
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Yes! I answered my own question. I tried the above and it works just fine.
This is an easy way for anyone to define hard surfaces.Posted 6 years ago # -
Glad you got it to work! I wondered about this some time ago when we noticed this behaviour during time reversal image reconstruction in heterogeneous media (see here), but never actually tried it. Did you need to do anything in particular other than using your object to define the positions in your source mask with u = 0?
Posted 6 years ago # -
Hi. I used time-dependent excitation signals for each point in the source and reflector 9the reflector's being all 0s), and just stacked them together in one source.u array.
As a post note, I got much better results with another method entirely; just setting the density of the reflector to very high. I thought this would make the solver unhappy, like it is when I set the reflector velocity higher than water, but it didn't seem to mind.
The results from method #1 (dirchelet) had more extraneous wiggles on the pressure traces, and the received pulses were not as clean.Posted 6 years ago #
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