k-Wave User Forum » Topic: Zero or exceptionally high pressure output from pstdElastic3D function

k-Wave User Forum » Topic: Zero or exceptionally high pressure output from pstdElastic3D function http://www.k-wave.org/forum/topic/zero-or-exceptionally-high-pressure-output-from-pstdelastic3d-function Support for the k-Wave MATLAB toolbox en-US Tue, 12 May 2026 22:00:30 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://www.k-wave.org/forum/search.php Bradley Treeby on "Zero or exceptionally high pressure output from pstdElastic3D function" http://www.k-wave.org/forum/topic/zero-or-exceptionally-high-pressure-output-from-pstdelastic3d-function#post-8963 Fri, 24 Nov 2023 17:52:59 +0000 Bradley Treeby 8963@http://www.k-wave.org/forum/ The simulation is unstable. Try reducing the time step (CFL). I tried CFL = 0.05 and it seemed to run ok. Amita on "Zero or exceptionally high pressure output from pstdElastic3D function" http://www.k-wave.org/forum/topic/zero-or-exceptionally-high-pressure-output-from-pstdelastic3d-function#post-8908 Mon, 11 Sep 2023 08:39:30 +0000 Amita 8908@http://www.k-wave.org/forum/ Hi, I am trying to simulate the pressure distribution in a viscoelastic medium using pstdElastic3D. When I am using a velocity source with a rectangular source mask and getting exceptionally high-pressure values (P_max). I am not sure where I am going wrong. Please help. Code is pasted below. clear; close all; clc; %Define the medium and grids (Sampling) L_x=(20*10^-3);% Unit:m L_y=(20*10^-3);% Unit:m L_z=(20*10^-3);% Unit:m C_L=1540; % compressional sound speed; unit: m/s Frequency_US=1*10^6; %unit: Hz (Maximum frequency) Wavelength_Min=C_L/Frequency_US; % Unit: m dx=Wavelength_Min/5; dy=dx; dz=dx; Nx=ceil(L_x/dx); % Number of grids in the x direction; ceil rounds the number to next integer. Ny=ceil(L_y/dy); % Number of grids in the y direction Nz=ceil(L_z/dz); % Number of grids in the z direction kgrid = kWaveGrid(Nx, dx, Ny, dy, Nz, dz); % kWavegrid class makes and store grid points %Assigning the temporal grids CFL=0.5; dt=CFL*dx/C_L;% CFL=c*dt/dx simulation_time=40*10^-6; % unit: seconds Nt=ceil(simulation_time/dt);% round-off to the next integer kgrid.setTime(Nt, dt);% it sets the time grid and makes time array %medium properties for pstdElastic3D medium.sound_speed_compression=C_L; %m/s medium.sound_speed_shear=1.7; %Unit: m/s medium.density=980; %in kg/m^3 medium.alpha_coeff_compression=0.1; %dB/MHz^2-cm medium.alpha_coeff_shear=0.3; %dB/MHz^2-cm %Defining the source input % define properties of the input signal source_strength = 1e-6; % [m/s] tone_burst_freq = Frequency_US; % [Hz] tone_burst_cycles = 5; input_signal = source_strength*toneBurst(1/kgrid.dt, tone_burst_freq, tone_burst_cycles); Transducer_height=46;% in grid points transducer_width = 32; source.u_mask = zeros(Nx, Ny, Nz); source.u_mask(11, ceil(Ny/2 - transducer_width/2) + 1:ceil(Ny/2 + transducer_width/2), ceil(Nz/2 - Transducer_height/2) + 1:ceil(Nz/2 + Transducer_height/2)) = 1 source.u_mode='dirichlet'; focus_position=[0, 0, 0]; focus_signal = focus(kgrid, input_signal, source.u_mask, focus_position, C_L); % plot(focuse_signal((93*0)+101,:)) source.ux=focus_signal; %focused_signal; %% define the sensor mask sensor.mask = zeros(Nx, Ny, Nz); %taking the sensor mask at the X-Y plane at the center of the medium (z=0 %plane) sensor.mask(:,:,round(Nz/2)) = 1; sensor.record = {'p', 'p_max', 'u', 'I', 'I_avg'}; sensor.record_start_index=1; %(default=1) %set input values for PML boundary layer alpha_coeff_PML=2.5; % dB/MHz-cm (default=2) PML_size=[10,10,10]; %(default=10) % set the optional input as input arguements input_args = {'PlotPML', false, 'PMLAlpha', alpha_coeff_PML, 'PMLSize', PML_size}; % RUN the elastic simulation %use pstdElastic3D function to simulate propagation of elastic wave in this %homogenous viscoelastic medium sensor_data=pstdElastic3D(kgrid, medium, source, sensor, input_args{:});