http://www.k-wave.org/forum/topic/question-about-the-accuracy-of-the-example-simulation-result Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 06:47:38 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/question-about-the-accuracy-of-the-example-simulation-result#post-5017 Mon, 23 Mar 2015 19:15:35 +0000 Bradley Treeby 5017@http://www.k-wave.org/forum/ <p>Hi Yu,</p> <p>As I mentioned before, the maximum supported frequency isn't an intrinsic property of the medium, but a constraint imposed by the discretisation. Think about an oscilloscope recording a signal - the maximum temporal frequency it can record is dictated by the sampling frequency or dt. The same is true in numerical models - the maximum spatial frequency that can be represented on the grid is dictated by the spatial sampling frequency or dx. For the wave equation, temporal and spatial frequency are related by the sound speed.</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/question-about-the-accuracy-of-the-example-simulation-result#post-5007 Mon, 16 Mar 2015 07:27:05 +0000 firetripper 5007@http://www.k-wave.org/forum/ <p>Dear Brad,<br /> My question is : the properties of the medium you simulated can not change when you change the size of grids. But now, when you change dx, the maximum supported frequency by the same medium simulated is changing. That contradicts with my common sense.<br /> Best,<br /> Yu </p> http://www.k-wave.org/forum/topic/question-about-the-accuracy-of-the-example-simulation-result#post-5004 Wed, 11 Mar 2015 10:21:16 +0000 Bradley Treeby 5004@http://www.k-wave.org/forum/ <p>Hi Yu,</p> <p>The values printed to the command line of the maximum supported frequency are calculated based on computational grid constraints, i.e., for a wave to be supported by the grid, it needs to be represented by at least two grid points per wavelength. The formula used is f_max = c / 2*dx. For the particular example you mention, setting c = 2 gives f_max of 10 kHz. Modifying the value of dx will change the maximum frequency supported.</p> <p>Hope that helps,</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/question-about-the-accuracy-of-the-example-simulation-result#post-4999 Mon, 02 Mar 2015 06:08:33 +0000 firetripper 4999@http://www.k-wave.org/forum/ <p>Dear Brad,<br /> In the example "example_ewp_plane_wave_absorption.m", edit the medium to uniform and edit the shear wave velocity to 2m/s, using impulse excitation. Then run the shear wave propagation. In this example, the maximum supported shear frequency is 10000Hz. It contradicts common sense. Because the medium which can support shear wave velocity 2m/s is softer than tofu. Thus, this medium can not support frequency 10000Hz. Now I wonder the accuracy of the simulation result and how to obtain an "accurate" frequency spectrum of simulated medium. Thanks so much!<br /> Best,<br /> Yu </p>