k-Wave User Forum » Topic: Pressure starting value and how to increase the frequency range of simulation

k-Wave User Forum » Topic: Pressure starting value and how to increase the frequency range of simulation http://www.k-wave.org/forum/topic/pressure-starting-value-and-how-to-increase-the-frequency-range-of-simulation Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 03:13:17 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://www.k-wave.org/forum/search.php manuelbcabo on "Pressure starting value and how to increase the frequency range of simulation" http://www.k-wave.org/forum/topic/pressure-starting-value-and-how-to-increase-the-frequency-range-of-simulation#post-5768 Fri, 25 Nov 2016 15:40:23 +0000 manuelbcabo 5768@http://www.k-wave.org/forum/ Thanks for the reply Brad, I know that I can increase the f_max value, but I obtain a pressure greater than amplitude of pressure that I put theoretically in input signal, even if I consider dirichlet condition in source.p_mode option. Manu Bradley Treeby on "Pressure starting value and how to increase the frequency range of simulation" http://www.k-wave.org/forum/topic/pressure-starting-value-and-how-to-increase-the-frequency-range-of-simulation#post-5767 Fri, 25 Nov 2016 13:51:17 +0000 Bradley Treeby 5767@http://www.k-wave.org/forum/ HI manuelbcabo, You can increase the maximum frequency by increasing the value of <code>f_max</code> in your code. Brad. manuelbcabo on "Pressure starting value and how to increase the frequency range of simulation" http://www.k-wave.org/forum/topic/pressure-starting-value-and-how-to-increase-the-frequency-range-of-simulation#post-5758 Tue, 22 Nov 2016 14:31:00 +0000 manuelbcabo 5758@http://www.k-wave.org/forum/ Hello all, I've seen that some people asked before me for this topic but I don't find the correct solution that works for me. I'm trying to obtain a relation among radius of radiating surface and parametric difference non linear beam generation. I've two main question about code that I show below. - I obtain a pressure of total beam pattern greater than I putted like a entry in my code. I've read in this forum that probably this can be solved using dirichlet option in source.p_mode but do not work in my case (Probably I miss something..). In any case I solved this problem finding a relationship between dx & dy and Nx & Ny. How can I solved this problem ? - With this relation that I found the maximum frequency that I can simulate is ~ 300kHz that is enough for difference frequency non linear beam but I would like observe also 2·f2 beam. How can I increase the frequency range validity of the simulation without losing good amplitude of pressure emitted (in order to no obtain greater amplitude that I putted like amplitude of bifrequency signal). I put my code below. Thanks in advance for your help. Cheers *************************************************************************************** Amp = [100 1000 10000 100000 500000 750000 1000000 2000000 3000000 4000000 5000000]; for i = 1:11 USE_STATISTICS = false; f_max = 170000; c0_min = 1482; points_per_wavelength = 3.5; x_size = 0.25; y_size = 0.5; dx = (c0_min/(points_per_wavelength*f_max)); Nx = round(x_size/dx); dy = (c0_min/(points_per_wavelength*f_max)); Ny = round(y_size/dy); kgrid = makeGrid(Nx, dx, Ny, dy); [kgrid.t_array, dt] = makeTime(kgrid, c0_min) medium.sound_speed = 1482*ones(Nx, Ny); % [m/s] medium.density = 1000*ones(Nx, Ny); % [kg/m^3] att1 = 2.17e-3; %Attenuation dB/cm·MHz2 medium.alpha_coeff=att1*ones(Nx, Ny); medium.alpha_power=2; medium.BonA = 4.96; radio_dist = 0.0375; r = radio_dist/dx; em_pos_y = round(0.01/dy); source.p_mask = zeros(Nx, Ny); source.p_mask(round((Nx/2)-r):round((Nx/2)+r),em_pos_y) = 1; f1 = 120000; f2 = 170000; Mag_Pa = Amp(i); signal = Mag_Pa.*(0.5.*sin(2*pi*f1.*kgrid.t_array) + 0.5.*sin(2*pi*f2.*kgrid.t_array)); source.p = signal; source.p_mode = 'dirichlet'; source.p = signal(1:375); source.p = filterTimeSeries(kgrid, medium, source.p); %% Define a Cartesian sensor mask Directividad sensor.mask = [1, 1, Nx, Ny].'; sensor.record = {'p','p_max'}; input_args = { 'DisplayMask', source.p_mask, 'RecordMovie', true, 'MovieType', 'image', 'MovieName', 'Directividad_Piston_2D', 'PMLInside', false, 'PlotScale', [-Mag_Pa-0.2*Mag_Pa, Mag_Pa+0.2*Mag_Pa]}; sensor_data = kspaceFirstOrder2D(kgrid, medium, source, sensor,input_args{:}); % Post-Procesado [freq, amp_spect] = spect(sensor_data.p, 1/dt, 'Dim', 3); %Compute and plot the fundamental beam [f1_value, f1_index] = findClosest(freq, f1); beam_pattern_f1 = amp_spect(:, :, f1_index); figure; subplot(2,2,1); imagesc((kgrid.y_vec+max(kgrid.y_vec)).*100, (kgrid.x_vec+max(kgrid.x_vec)).*100, sensor_data.p_max); colormap(jet(1024)); colorbar ylabel('x-position [cm]'); xlabel('y-position [cm]'); title('Total Beam Pattern'); axis image; %Compute and plot the difference beam diff_freq = f2-f1; [f2_value, f2_index] = findClosest(freq, diff_freq); beam_pattern_f2 = amp_spect(:, :, f2_index); subplot(2,2,2);imagesc((kgrid.y_vec+max(kgrid.y_vec)).*100, (kgrid.x_vec+max(kgrid.x_vec)).*100, beam_pattern_f2, [0 0.025*Mag_Pa]); colormap(jet(1024)); colorbar ylabel('x-position [cm]'); xlabel('y-position [cm]'); axis image; title('f_2-f_1 Beam Pattern'); %Compute and plot the difference beam diff2_freq = 2*f1; [f3_value, f3_index] = findClosest(freq, diff2_freq); beam_pattern_f3 = amp_spect(:, :, f3_index); subplot(2,2,3);imagesc((kgrid.y_vec+max(kgrid.y_vec)).*100, (kgrid.x_vec+max(kgrid.x_vec)).*100, beam_pattern_f3); colormap(jet(1024)); colorbar ylabel('x-position [cm]'); xlabel('y-position [cm]'); axis image; title('2·f1 Beam Pattern'); %Compute and plot the difference beam f1_f2_freq = f1+f2; [f4_value, f4_index] = findClosest(freq, f1_f2_freq); beam_pattern_f4 = amp_spect(:, :, f4_index); subplot(2,2,4);imagesc((kgrid.y_vec+max(kgrid.y_vec)).*100, (kgrid.x_vec+max(kgrid.x_vec)).*100, beam_pattern_f4); colormap(jet(1024)); colorbar ylabel('x-position [cm]'); xlabel('y-position [cm]'); axis image; title('f1 + f2 Beam Pattern'); end