http://www.k-wave.org/forum/topic/simulating-two-3mhz-divergent-transducers-in-3d Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 00:52:46 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/simulating-two-3mhz-divergent-transducers-in-3d#post-3788 Wed, 17 Jul 2013 21:33:15 +0000 yguo 3788@http://www.k-wave.org/forum/ <p>Wait, I think I did it! Just took some playing around. Thanks again! </p> http://www.k-wave.org/forum/topic/simulating-two-3mhz-divergent-transducers-in-3d#post-3787 Wed, 17 Jul 2013 20:21:51 +0000 yguo 3787@http://www.k-wave.org/forum/ <p>Hi Ben,</p> <p>Thanks for your response! I will give vector velocity sources a try. I'm still a bit confused about the method for time series. In the example you post, all source points in the source mask are set to a time varying input of 250kHz. </p> <p>I've defined a binary source mask that places two parallel lines on the grid. If I'm understanding correctly, in order to have one line's source input be a different frequency from the other line, I need to:<br /> - figure out the indexing of my two lines in source.p, based on MATLAB's column-wise indexing<br /> - create a matrix of time series for source.p that corresponds to the source point indexing</p> <p>Is this the right idea? </p> http://www.k-wave.org/forum/topic/simulating-two-3mhz-divergent-transducers-in-3d#post-3784 Tue, 16 Jul 2013 11:15:03 +0000 bencox 3784@http://www.k-wave.org/forum/ <p>Hi yguo,</p> <p>You can define vector velocity sources, as well as pressure sources, so you can make the transmission directional. You can also apply a different time series to each source point in the grid. This is from the documentation:</p> <p>"An initial pressure distribution can be specified by assigning a matrix (the same size as the computational grid) of arbitrary numeric values to <code>source.p0</code>. A time varying pressure source can similarly be specified by assigning a binary matrix (i.e., a matrix of 1's and 0's with the same dimensions as the computational grid) to <code>source.p_mask</code> where the 1's represent the grid points that form part of the source. The time varying input signals are then assigned to <code>source.p</code>. This must be the same length as <code>kgrid.t_array</code> and can be a single time series (in which case it is applied to all source elements), or a matrix of time series following the source elements using MATLAB's standard column-wise linear matrix index ordering. A time varying velocity source can be specified in an analogous fashion, where the source location is specified by <code>source.u_mask</code>, and the time varying input velocity is assigned to <code>source.ux</code>, <code>source.uy</code>, and <code>source.uz</code>."</p> <p>You change the frequency of the source by changing the time series allocated to <code>source.p</code>, <code>source.ux</code>, etc. See for example <a href="http://www.k-wave.org/documentation/example_tvsp_homogeneous_medium_monopole.php">this example</a>. In fact, you're not even restricted to a single frequency, you can use any arbitrary time series you like.</p> <p>Good luck with your simulations!</p> <p>Ben </p> http://www.k-wave.org/forum/topic/simulating-two-3mhz-divergent-transducers-in-3d#post-3779 Mon, 15 Jul 2013 16:51:50 +0000 yguo 3779@http://www.k-wave.org/forum/ <p>Hello,</p> <p>Thank you for making this toolbox; it's been a lot of fun exploring the features. I'm only about halfway through the tutorial now, but I figured it couldn't hurt to ask for help on my project.</p> <p>I'm attempting to model two single element 3MHz transducers in the shape of flattened domes (think of a circular cutout on the surface of a sphere). They'll be angled towards each other about 30 degrees; I want to see their beam field patterns interact. I'm confident that I can create two sources in that shape and then place them in a 3D grid with a medium simulating soft tissue.</p> <p>However, I'm unclear about other aspects. The sources I've tried making so far all emitting omnidirectional. Is there a way I can limit sources to one direction, say using a vector, and have a limited degree of beam divergence? Also, is there a way for me to change the frequency of one source? I've only been able to program 3MHz from every source.</p> <p>Any insight into these questions would be very appreciated.</p> <p>Thank you kindly. </p>