Hey,
i got an issue using "example_tvsp_homogeneous_medium_monopole.m". When i double the number of grid points but leaving the rest, the pressure amplitude at the sensor doubles.
It should stay at the same value since the source and the distance in between both stays.
Seems to be a bug to me, can someone help here?
greets
Jan
Hi Jan,
This isn't a bug, but I agree it's potentially confusing. It's to do with the fact that what you are putting into k-Wave as a source is different if dx is different. It's important to understand what it means to put a source at a grid point in k-Wave (or other collocation methods). What k-Wave sees is not a source at a single point but the bandlimited version of that point source. One implication is that the source is non-zero in between the grid points (which you can't see when plotting just the pressure on the grid points). To account for this we include a scaling factor in k-Wave. There's a longer explanation here of what that scaling factor is, and with details of how to remove that scaling factor if you want to:
http://www.k-wave.org/forum/topic/using-sourcep-to-specify-pressure-distribution#post-4181.
Best wishes
Ben
Hey Ben,
Thanks for your fast reply. In my words I understand it like this:
If there's a 2D grid with dx = dy = 1m with a varying pressure amplitude, the acoustic energy is 4 times higher as if the grid was dx = dy = 0.5m. It's not a single point that emits energy, it's a whole cell and it's size matters. I'll try to deal with that.
Thanks!
Jan
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