http://www.k-wave.org/forum/topic/noisy-acoustic-waves-in-heterogenous-medium Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 03:49:32 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/noisy-acoustic-waves-in-heterogenous-medium#post-8033 Sun, 31 Jan 2021 17:57:58 +0000 Farzin 8033@http://www.k-wave.org/forum/ <p>Thank you for the informative hint and the reference. </p> http://www.k-wave.org/forum/topic/noisy-acoustic-waves-in-heterogenous-medium#post-8030 Wed, 27 Jan 2021 23:31:58 +0000 Bradley Treeby 8030@http://www.k-wave.org/forum/ <p>Hi Farzin,</p> <p>By default, the reference sound speed used in the k-space operator is set to the maximum to make the simulation unconditionally stable. However, because most of the medium is 1500 m/s in your simulation, this means dispersion errors accumulate. Try setting <code>medium.sound_speed_ref = 1500</code> (or alternatively reduce the size of the time step) and it should solve the problem. See <a href="http://www.k-wave.org/papers/2012-Treeby-JASA.pdf">here</a> (Sec V.A) if you want to read more.</p> <p>Brad </p> http://www.k-wave.org/forum/topic/noisy-acoustic-waves-in-heterogenous-medium#post-8026 Mon, 25 Jan 2021 11:57:08 +0000 Farzin 8026@http://www.k-wave.org/forum/ <p>Dear Brad,</p> <p>Thank you for your response. The attached codes are a simplified example in MATLAB.</p> <p>Farzin</p> <p>P.S. The output figure: <a href="https://i.ibb.co/MR2KDCZ/transducer-ct-pt.png" rel="nofollow">https://i.ibb.co/MR2KDCZ/transducer-ct-pt.png</a></p> <p>Nz = 560;<br /> Nr = 125;<br /> kgrid = kWaveGrid(Nz, 1e-04, Nr, 1e-4);<br /> source.p0 = zeros (Nz, Nr);<br /> source.p0(30:100,1:50) = 1;<br /> sensor.mask = [520;1;530;95];<br /> medium.sound_speed = 1500 * ones(Nz, Nr);<br /> medium.density = 1000 * ones(Nz, Nr);<br /> sensor_data_hom = kspaceFirstOrderAS(kgrid, medium, source, sensor);</p> <p>medium.sound_speed(520:end,:) = 2200;<br /> medium.density(520:end,:) = 1780;<br /> sensor_data_het = kspaceFirstOrderAS(kgrid, medium, source, sensor);</p> <p>figure('Name','Trace from center of transducer');<br /> plot(kgrid.t_array*1e6,squeeze(sensor_data_hom(1).p(1, 1, :)), 'r-');<br /> xlabel('Time (us)');<br /> ylabel('Pressure');<br /> hold on<br /> plot(kgrid.t_array*1e6,squeeze(sensor_data_het(1).p(1, 1, :)), 'b-');<br /> legend('Homogenous', 'Heterogeneous');<br /> axis tight;<br /> hold off </p> http://www.k-wave.org/forum/topic/noisy-acoustic-waves-in-heterogenous-medium#post-8022 Sun, 24 Jan 2021 18:16:42 +0000 Bradley Treeby 8022@http://www.k-wave.org/forum/ <p>Hi Farzin,</p> <p>Can you post some more details (or preferably a simple example) of what you mean?</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/noisy-acoustic-waves-in-heterogenous-medium#post-8019 Fri, 22 Jan 2021 17:49:24 +0000 Farzin 8019@http://www.k-wave.org/forum/ <p>I am trying to simulate the photoacoustic signals detected by an ultrasound transducer. The 2D axisymmetric geometry consists of the carrier medium, water, and a transducer. I fed pressure as an initial value to k-wave. </p> <p>While running the solver, the acoustic waves look similar to the literature in the case of a homogenous medium. However, after adding the second medium, i.e., the transducer's physical properties, the propagating acoustic waves get noisy. </p> <p>I appreciate any help in this regard. </p>