k-Wave User Forum » Topic: Differences in focus pressure between k-Wave and analytical transducer model

k-Wave User Forum » Topic: Differences in focus pressure between k-Wave and analytical transducer model http://www.k-wave.org/forum/topic/differences-in-focus-pressure-between-k-wave-and-analytical-transducer-model Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 00:14:34 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://www.k-wave.org/forum/search.php Deepak Sonker on "Differences in focus pressure between k-Wave and analytical transducer model" http://www.k-wave.org/forum/topic/differences-in-focus-pressure-between-k-wave-and-analytical-transducer-model#post-8283 Fri, 06 Aug 2021 21:03:18 +0000 Deepak Sonker 8283@http://www.k-wave.org/forum/ Thank you I have got the correct pressure with kWaveArray class. Bradley Treeby on "Differences in focus pressure between k-Wave and analytical transducer model" http://www.k-wave.org/forum/topic/differences-in-focus-pressure-between-k-wave-and-analytical-transducer-model#post-8254 Wed, 21 Jul 2021 16:13:41 +0000 Bradley Treeby 8254@http://www.k-wave.org/forum/ Hi deepak11, There are some examples of doing this comparison in the new <a href="http://www.k-wave.org/forum/topic/alpha-version-of-kwavearray-off-grid-sources">kWaveArray</a> class that might show you where you're going wrong. Note, if you're using a grid-based source, you'll have to include an extra scaling factor (or weight the source amplitudes) as discuss in <a href="http://bug.medphys.ucl.ac.uk/papers/2016-Martin-IEEETUFFC.pdf">this paper</a>. Brad deepak11 on "Differences in focus pressure between k-Wave and analytical transducer model" http://www.k-wave.org/forum/topic/differences-in-focus-pressure-between-k-wave-and-analytical-transducer-model#post-8244 Tue, 20 Jul 2021 23:51:29 +0000 deepak11 8244@http://www.k-wave.org/forum/ Hi, First of all thank you for building this amazing toolbox. I have simulated the bowel transducer in 3D and then compared the focus pressure amplitude with the analytical model of a concave spherical transducer (from Theory of Focusing Radiators by H.T. O'Neil). I also checked this analytical model results from the Sonic Concepts transducer (H-276) and it was correct. I couldn't find the mistake in my code I think I have done everything correctly but the results shouldn't deviate that much (like the peak pressure at the focus must be 58 MHz but the simulated pressure is 46.8 MHz ). I have posted the code below: (`% define the grid parameters 3D Nx = 150; % [grid points] Ny = 150; % [grid points] Nz = 92; dx = 0.1e-3; % [m] dy = 0.1e-3; % [m] dz = 0.1e-3; % [m] % create the computational grid kgrid = kWaveGrid(Nx, dx, Ny, dy, Nz, dz); % define the properties of the propagation medium water medium.sound_speed = 1500; % [m/s] medium.density = 1000; % [kg/m^3] medium.alpha_coeff = 0.025; % [dB/(MHz^y cm)] medium.alpha_power = 1.5; % define parameters grid_size = [150,150,92]; bowl_pos = [Nx/2, Ny/2, 2]; diameter = 15e-3; % [m] radius = 8.5e-3; % [m] focus_pos = [Nx/2, Ny/2, 87]; freq = 1.5e6; % [Hz] amp = 2.06e6; % [Pa] % create bowl source.p_mask = makeBowl(grid_size, bowl_pos, round(radius / dx), round(diameter / dx)+1, focus_pos, 'Plot', true); % calculate the time step using an integer number of points per period ppw = max(medium.sound_speed(:)) / (freq * dx); % points per wavelength cfl = 0.3; % cfl number ppp = ceil(ppw / cfl); % points per period T = 1 / freq; % period [s] dt = T / ppp; % time step [s] % calculate the number of time steps to reach steady state t_end = sqrt( kgrid.x_size.^2 + kgrid.y_size.^2 + kgrid.z_size.^2 ) / max(medium.sound_speed(:)); Nt = round(t_end / dt); % create the time array kgrid.setTime(Nt, dt); % define the input signal source.p = createCWSignals(kgrid.t_array, freq, amp, 0); % set the sensor mask to cover the entire grid sensor.mask = ones(Nx, Ny, Nz); sensor.record = {'p','p_rms','u','u_rms', 'I','I_avg'}; % record the last 3 cycles in steady state num_periods = 3; T_points = round(num_periods * T / kgrid.dt); sensor.record_start_index = Nt - T_points + 1; % set the input arguements input_args = {'PMLInside', false, 'PlotPML', false, 'DisplayMask', ... 'off', 'PlotScale', [-1, 1] * amp}; % run the acoustic simulation sensor_data = kspaceFirstOrder3D(kgrid, medium, source, sensor, input_args{:}); % convert the absorption coefficient to nepers/m alpha_np = db2neper(medium.alpha_coeff, medium.alpha_power) * ... (2 * pi * freq).^medium.alpha_power; % extract the pressure amplitude at each position p = extractAmpPhase(sensor_data.p, 1/kgrid.dt, freq); % reshape the data, and calculate the volume rate of heat deposition p = reshape(p, Nx, Ny, Nz);