http://www.k-wave.org/forum/topic/ripple-problem Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 02:27:19 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/ripple-problem#post-7721 Wed, 05 Aug 2020 11:18:57 +0000 Bradley Treeby 7721@http://www.k-wave.org/forum/ <p>Hi Andrea,</p> <p>A couple of things to keep in mind.<br /> (1) As k-Wave is a time domain solver, to simulate the pressure field at a single frequency, you need to run the simulation for some time, e.g., to allow the waves from all parts of the transducer to propagate to all parts of the domain.<br /> (2) If you record <code>p_max_all</code> for the complete simulation, you will be taking the maximum pressure not just in steady state, but also over the transient parts while the steady state fields builds up. </p> <p>Some things you can try:<br /> - Increase the simulation time<br /> - Set <code>sensor.record_start_index</code> to only take <code>p_max_all</code> when the field has reached steady state<br /> - Record <code>sensor.p</code> over an integer number of cycles in steady state, and then extract the amplitude using <code>extractAmpPhase</code>, e.g., as in the <a href="http://www.k-wave.org/documentation/example_diff_focused_ultrasound_heating.php">Heating By A Focused Ultrasound Transducer</a>. This is the best option if you want the field precisely, although using <code>p_max_all</code> will give a similar result provided you set <code>sensor.record_start_index</code> and have a small enough time step such that the wave is well sampled.</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/ripple-problem#post-7677 Mon, 29 Jun 2020 15:25:08 +0000 Andrea Addison 7677@http://www.k-wave.org/forum/ <p>Hello Dr.Treeby,</p> <p>I am using pstdElastic2D. The figures are the results of the 'p_max_all'.</p> <p>Best regards,<br /> Andrea </p> http://www.k-wave.org/forum/topic/ripple-problem#post-7659 Sat, 27 Jun 2020 13:41:50 +0000 Bradley Treeby 7659@http://www.k-wave.org/forum/ <p>Hi Andrea,</p> <p>Which code are you using, <code>kspaceFirstOrder2D</code> or <code>acousticFieldPropagator</code>?</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/ripple-problem#post-7637 Wed, 24 Jun 2020 00:45:59 +0000 Andrea Addison 7637@http://www.k-wave.org/forum/ <p>Hello Dr.Treeby,</p> <p>Thanks for this useful toolbox. In the URL's image, I see ripples on top of the maximum pressure image. When I increase the dimensions, it disappears. But it makes the completion time longer. I was wondering what is the reason for these ripples and how I can eliminate them in the smaller dimension case? The maximum pressure figures are here: <a href="https://imgur.com/a/3rOQnYF" rel="nofollow">https://imgur.com/a/3rOQnYF</a></p> <p>Best regards,<br /> Andrea </p>