k-Wave User Forum » Topic: Simulation of the reflected acoustic waves from a moving object inside a room

k-Wave User Forum » Topic: Simulation of the reflected acoustic waves from a moving object inside a room http://www.k-wave.org/forum/topic/simulation-of-the-reflected-acoustic-waves-from-a-moving-object-inside-a-room Support for the k-Wave MATLAB toolbox en-US Tue, 12 May 2026 23:32:11 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://www.k-wave.org/forum/search.php Bradley Treeby on "Simulation of the reflected acoustic waves from a moving object inside a room" http://www.k-wave.org/forum/topic/simulation-of-the-reflected-acoustic-waves-from-a-moving-object-inside-a-room#post-4537 Thu, 22 May 2014 15:08:40 +0000 Bradley Treeby 4537@http://www.k-wave.org/forum/ Hi bashjokh, It is certainly possible to make a source move within the grid, however, it is not completely trivial to code. The basic idea is to vary the source signal used for each grid point within the source mask over time. There is an example of how to do this in the toolbox as part of the <a href="http://www.k-wave.org/documentation/example_tvsp_doppler_effect.php">Doppler Effect Example</a>. You might also find <a href="http://www.k-wave.org/forum/topic/doppler-effect-of-the-source">this post</a> useful. Brad. bashjokh on "Simulation of the reflected acoustic waves from a moving object inside a room" http://www.k-wave.org/forum/topic/simulation-of-the-reflected-acoustic-waves-from-a-moving-object-inside-a-room#post-4511 Sun, 11 May 2014 20:52:42 +0000 bashjokh 4511@http://www.k-wave.org/forum/ Hi, I'm new to k-wave, and i'm trying now to simulate the recorded sound waves from a moving object in a room. As start point I have used the following code: clear all; % set the PML size PML_size = 20; % create the computational grid [ 3m by 3m domain ] Nx = 128 - 2*PML_size; % number of grid points in the x (row) direction Ny = 128 - 2*PML_size; % number of grid points in the y (column) direction dx = 3/Nx; % grid point spacing in the x direction [m] dy = 3/Ny; % grid point spacing in the y direction [m] kgrid = makeGrid(Nx, dx, Ny, dy); % define the properties of the propagation medium c_air = 330; % [m/s] sound speed rho_air = 1.225; % [kg/m^3] density % define the properties of the object c_object = 1000; % [m/s] rho_object = 1000; % [kg/m^3] thickness = 5; % [grid points] % define the position of the object object_y_pos = Ny/2; object_x_pos = Nx/4; object= zeros(Nx, Ny); object(object_x_pos : end - end/4, object_y_pos : end - end/2 + thickness) = 1; % assign the medium properties medium.sound_speed = c_air*ones(Nx, Ny); medium.sound_speed(object == 1) = c_object; medium.density = rho_air*ones(Nx, Ny); medium.density(object == 1) = rho_object; % set the velocity of the moving object obj_vel = 150; % [m/s] % set the reference sound speed used in the k-space operator medium.sound_speed_ref = c_air; % create the time array cfl = 0.2; %Courant-Friedrichs-Lewy number t_end = 20e-3; % [s] [kgrid.t_array, dt] = makeTime(kgrid, medium.sound_speed, cfl, t_end); % define a time varying sinusoidal source %source_freq = 1.5e3; % [Hz] source_mag = 50; % [Pa] %source.p = source_mag*sin(2*pi*source_freq*kgrid.t_array); % define a tone burst sampling_freq = 1/dt; % [Hz] tone_burst_freq = 1.5e3; % [Hz] tone_burst_cycles = 3; source.p = source_mag*toneBurst(sampling_freq, tone_burst_freq, tone_burst_cycles); % define a single source point source.p_mask = zeros(Nx, Ny); source.p_mask(end/2, end/4) = 1; % define sensor point sensor.mask = zeros(Nx, Ny); sensor.mask(end/2, end/4) = 1; display_mask = object + sensor.mask; % define the acoustic parameters to record %sensor.record = {'p'}; % run simulation sensor_data = kspaceFirstOrder2D(kgrid, medium, source, sensor, ... 'PMLInside', false, 'PlotPML', false, 'PMLSize', PML_size, ... 'DisplayMask', display_mask, 'PlotScale', [-0.25, 0.25]*source_mag,... 'DataCast', 'single'); % plot the recorded data figure; subplot(2, 1, 1); [t_sc scale prefix] = scaleSI(max(kgrid.t_array(:))); plot(source.p, 'b-'); xlabel(['Time [' prefix 's]']); ylabel('Signal Amplitude'); axis tight; title('Source Pressure Signal'); subplot(2, 1, 2), plot(kgrid.t_array*scale, sensor_data, 'r-'); xlabel(['Time [' prefix 's]']); ylabel('Signal Amplitude'); axis tight; title('Sensor Pressure Signal'); and now I ca not know how to let the object move inside the computational grid. I will appreciate any help! Best Regards