k-Wave User Forum » Topic: I want to eliminate the signal reflected from the boundary.

k-Wave User Forum » Topic: I want to eliminate the signal reflected from the boundary. http://www.k-wave.org/forum/topic/i-want-to-eliminate-the-signal-reflected-from-the-boundary Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 12:06:38 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://www.k-wave.org/forum/search.php Bradley Treeby on "I want to eliminate the signal reflected from the boundary." http://www.k-wave.org/forum/topic/i-want-to-eliminate-the-signal-reflected-from-the-boundary#post-7092 Fri, 18 Oct 2019 20:21:31 +0000 Bradley Treeby 7092@http://www.k-wave.org/forum/ Hi dnrdyd0379, Your source is inside the PML and the plot scale is saturated. Try: <pre><code>% run the simulation sensor_data = pstdElastic2D(kgrid, medium, source, sensor, ... 'PMLInside', false, ... 'PMLSize', 12, ... 'PlotScale', [-1, 1] * 1e3);</code></pre> Brad dnrdyd0379 on "I want to eliminate the signal reflected from the boundary." http://www.k-wave.org/forum/topic/i-want-to-eliminate-the-signal-reflected-from-the-boundary#post-7069 Tue, 08 Oct 2019 04:34:51 +0000 dnrdyd0379 7069@http://www.k-wave.org/forum/ A general note about the code is to have 5 MHz as the tone_burst. Mix different materials in the grid. I wrote the code for the above general points and the code looks like this: When you run it, you will see the source move from bottom to top in addition to moving from top to bottom. How do you solve this? % three Ultrafinedust in u_mask code clear all clc % create the computational grid Nx = 300; % [grid points] Ny = 300; % [grid points] %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% dx = 6.86e-6; % [m] %% See changes. dy = 6.86e-6; % [m] %% See changes. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% kgrid = makeGrid(Nx, dx, Ny, dy); % define the compressional sound speed [m/s] medium.sound_speed_compression = 343*ones(Nx, Ny); % define the shear sound speed [m/s] medium.sound_speed_shear = 0*ones(Nx, Ny); % define the mass density [kg/m?3] medium.density = 1.2754*ones(Nx, Ny); medium.density(150,50) = 2650; medium.density(150,100) = 2650; medium.density(150,150) = 2650; medium.density(150,200) = 2650; medium.density(150,250) = 2650; % define the absorption coefficients [dB/(MHz?2 cm)] medium.alpha_coeff_compression = 0; medium.alpha_coeff_shear = 0; %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%% Create the time array (Refer to Manual Page 31) kgrid.t_array = makeTime(kgrid, medium.sound_speed_compression, 0.05, 9e-6); %kgrid.t_array = makeTime(kgrid, medium.sound_speed_compression, CFL, t_end); % See this addition. % 0.1 is the CFL number, and 10e-6 is the t_end (total time duration). %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % define a tone burst and assign it to the x-direction particle velocity source.u_mask = zeros(Nx,Ny); source.u_mask(5,:) = 1; source.u_mode = 'additive'; %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% dt = kgrid.t_array(2)-kgrid.t_array(1) ; %[Hz] %%%% % See changes. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% sampling_freq = 1/dt; % [Hz] tone_burst_freq = 5e6; % [Hz] tone_burst_cycles = 3; source.ux = toneBurst(sampling_freq, tone_burst_freq, tone_burst_cycles); source.uy = toneBurst(sampling_freq, tone_burst_freq, tone_burst_cycles); toneBurst(sampling_freq, tone_burst_freq, tone_burst_cycles, 'Plot', true); % define a 2D binary sensor mask in the shape of a line x_offset = 25; % [grid points] width = 50; % [grid points] sensor.mask = zeros(Nx, Ny); sensor.mask(Nx-1, 1:Ny) = 1; % run the simulation sensor_data = pstdElastic2D(kgrid, medium, source, sensor);