k-Wave User Forum » Topic: Ultrasound heating does not work in a heteregeneous

k-Wave User Forum » Topic: Ultrasound heating does not work in a heteregeneous http://www.k-wave.org/forum/topic/ultrasound-heating-does-not-work-in-a-heteregeneous Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 08:27:01 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://www.k-wave.org/forum/search.php Bradley Treeby on "Ultrasound heating does not work in a heteregeneous" http://www.k-wave.org/forum/topic/ultrasound-heating-does-not-work-in-a-heteregeneous#post-7559 Sat, 06 Jun 2020 14:38:28 +0000 Bradley Treeby 7559@http://www.k-wave.org/forum/ Hi hamram, I would instead start with defining your desired PPW, and then use this to calculate the required grid spacing <code>dx</code> based on the same formula and a reference sound speed (e.g., the sound speed in the background). Brad. hamram on "Ultrasound heating does not work in a heteregeneous" http://www.k-wave.org/forum/topic/ultrasound-heating-does-not-work-in-a-heteregeneous#post-7523 Fri, 22 May 2020 06:06:20 +0000 hamram 7523@http://www.k-wave.org/forum/ I am trying to get the heating by ultrasound example working but in a 2D heterogeneous medium., but it does not work. I think the problem is that defining time arrey (kgrid.setTime) depends on Nt and dt and they also depend on ppp which is a matrix and not a single integer anymore. Is there a way to fix this? I appreciate any hint. Here is the code I use but does not work: clearvars; % ========================================================================= % ACOUSTIC SIMULATION % ========================================================================= % define the PML size pml_size = 20; % [grid points] % define the grid parameters Nx = 256 - 2 * pml_size; % [grid points] Ny = 256 - 2 * pml_size; % [grid points] dx = 0.25e-3; % [m] dy = 0.25e-3; % [m] % create the computational grid kgrid = kWaveGrid(Nx, dx, Ny, dy); % define the properties of the propagation medium medium.alpha_coeff = 0.75; % [dB/(MHz^y cm)] medium.alpha_power = 1.5; medium.sound_speed = 1500 * ones(Nx, Ny); % [m/s] medium.sound_speed(1:Nx/2, :) = 1800; % [m/s] medium.density = 1000 * ones(Nx, Ny); % [kg/m^3] medium.density(:, Ny/4:Ny) = 1200; % [kg/m^3] % define the source parameters diameter = 45e-3; % [m] radius = 35e-3; % [m] freq = 1e6; % [Hz] amp = 0.5e6; % [Pa] % define a focused ultrasound transducer source.p_mask = makeArc([Nx, Ny], [1, Ny/2], round(radius / dx), round(diameter / dx) + 1, [Nx/2, Ny/2]); % calculate the time step using an integer number of points per period ppw = 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 ) / 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); sensor.record = {'p', 'p_max_all'}; % 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 = kspaceFirstOrder2D(kgrid, medium, source, sensor, input_args{:});