http://www.k-wave.org/forum/topic/doubling-grid-points-halves-measured-pressure-amplitude-in-monopole-example Support for the k-Wave MATLAB toolbox en-US Tue, 12 May 2026 22:33:27 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/doubling-grid-points-halves-measured-pressure-amplitude-in-monopole-example#post-8895 Wed, 16 Aug 2023 15:54:39 +0000 jansi143 8895@http://www.k-wave.org/forum/ <p>Hey Ben,</p> <p>Thanks for your fast reply. In my words I understand it like this:</p> <p>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.</p> <p>Thanks!<br /> Jan </p> http://www.k-wave.org/forum/topic/doubling-grid-points-halves-measured-pressure-amplitude-in-monopole-example#post-8894 Tue, 15 Aug 2023 19:23:16 +0000 bencox 8894@http://www.k-wave.org/forum/ <p>Hi Jan,</p> <p>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:<br /> <a href="http://www.k-wave.org/forum/topic/using-sourcep-to-specify-pressure-distribution#post-4181">http://www.k-wave.org/forum/topic/using-sourcep-to-specify-pressure-distribution#post-4181</a>.</p> <p>Best wishes<br /> Ben </p> http://www.k-wave.org/forum/topic/doubling-grid-points-halves-measured-pressure-amplitude-in-monopole-example#post-8893 Tue, 15 Aug 2023 10:04:58 +0000 jansi143 8893@http://www.k-wave.org/forum/ <p>Hey,</p> <p>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.<br /> It should stay at the same value since the source and the distance in between both stays.</p> <p>Seems to be a bug to me, can someone help here?</p> <p>greets<br /> Jan </p>