http://www.k-wave.org/forum/topic/artefacts-when-changing-from-initial-pressure-to-varying-stress-source Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 05:21:03 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/artefacts-when-changing-from-initial-pressure-to-varying-stress-source#post-5932 Sun, 21 May 2017 15:37:55 +0000 Bradley Treeby 5932@http://www.k-wave.org/forum/ <p>Hi g.schober,</p> <p>You should set <code>source.sxx = source.syy;</code>, rather than <code>source.sxx = -source.syy;</code>. As an aside, your source is also within the PML.</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/artefacts-when-changing-from-initial-pressure-to-varying-stress-source#post-5921 Wed, 10 May 2017 08:19:00 +0000 g.schober@skz.de 5921@http://www.k-wave.org/forum/ <p>Hi @all,<br /> I have a problem when changing the type of source in the Example Explosive Source In A Layered Medium, I get two 'sources' at the medium changes that are not disappearing.<br /> <pre><code>Nx = 256; % number of grid points in the x (row) direction Ny = 256; % number of grid points in the y (column) direction dx = 0.1e-3; % grid point spacing in the x direction [m] dy = 0.1e-3; % grid point spacing in the y direction [m] kgrid = makeGrid(Nx, dx, Ny, dy); % define the properties of the upper layer of the propagation medium medium.sound_speed_compression = 1500*ones(Nx, Ny); % [m/s] medium.sound_speed_shear = zeros(Nx, Ny); % [m/s] medium.density = 1000*ones(Nx, Ny); % [kg/m^3] % define the properties of the lower layer of the propagation medium medium.sound_speed_compression(Nx/2:end, :) = 2000; % [m/s] medium.sound_speed_shear(Nx/2:end, :) = 800; % [m/s] medium.density(Nx/2:end, :) = 1200; % [kg/m^3] % define the absorption properties medium.alpha_coeff_compression = 0.1; % [dB/(MHz^2 cm)] medium.alpha_coeff_shear = 0.5; % [dB/(MHz^2 cm)] % create the time array cfl = 0.1; % Courant-Friedrichs-Lewy number t_end = 20e-6; % [s] kgrid.t_array = makeTime(kgrid, max(medium.sound_speed_compression(:)), cfl, t_end); % create initial pressure distribution using makeDisc disc_magnitude = 5; % [Pa] disc_x_pos = 30*128/Nx; % [grid points] disc_y_pos = Ny/2; % [grid points] disc_radius = 5*128/Nx; % [grid points] source.s_mask = makeDisc(Nx, Ny, disc_x_pos, disc_y_pos, disc_radius); source.syy=1e-3*filterTimeSeries(kgrid,medium,toneBurst(1/kgrid.dt,218e3,1)); source.syy=[source.syy,0 0 0 0 ]; source.sxx=-source.syy; % source.s_mode=&#39;dirichlet&#39;; % define a centered circular sensor sensor.mask = makeCircle(Nx, Ny, Nx/2, Ny/2, 20); % define a custom display mask showing the position of the interface from % the fluid side display_mask = false(Nx, Ny); display_mask(Nx/2 - 1, :) = 1; % define input arguments input_args = {&#39;PlotScale&#39;, [-0.25, 0.25, -0.05, 0.05], &#39;PlotPML&#39;, false,... &#39;DisplayMask&#39;, display_mask,&#39;DataCast&#39;,&#39;gpuArray-single&#39;,&#39;DataRecast&#39;,true}; % run the simulation sensor_data = pstdElastic2D(kgrid, medium, source, sensor, input_args{:}); %% reorder the simulation data sensor_data_reordered = reorderSensorData(kgrid, sensor, gather(sensor_data)); % ========================================================================= % VISUALISATION % ========================================================================= % plot source, sensor, and position of the interface % figure; % imagesc(kgrid.y_vec*1e3, kgrid.x_vec*1e3, double(source.p0 | sensor.mask | display_mask), [-1 1]); % colormap(getColorMap); % ylabel(&#39;x-position [mm]&#39;); % xlabel(&#39;y-position [mm]&#39;); % axis image; %% plot the re-ordered sensor data figure; imagesc(sensor_data_reordered,[-1e-6 1e-6]); colormap(getColorMap); ylabel(&#39;Sensor Position&#39;); xlabel(&#39;Time Step&#39;); colorbar;</code></pre>