k-Wave User Forum » Topic: hi

k-Wave User Forum » Topic: hi http://www.k-wave.org/forum/topic/hi-1 Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 01:33:14 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://www.k-wave.org/forum/search.php Bradley Treeby on "hi" http://www.k-wave.org/forum/topic/hi-1#post-4977 Wed, 04 Feb 2015 23:56:41 +0000 Bradley Treeby 4977@http://www.k-wave.org/forum/ Hi Mohsen, The code is not normalised in any way. If your source is defined in units of pressure [Pa], then your output will also be in units of pressure. Brad. mohsen on "hi" http://www.k-wave.org/forum/topic/hi-1#post-4965 Wed, 28 Jan 2015 21:15:53 +0000 mohsen 4965@http://www.k-wave.org/forum/ hello dr brad so far i was successful with your guidance in understanding of this problem. so one point for me is missing is that this code so for normilized problem? because when i try to run with normal values ,outputs are completely deferent best mohsen Bradley Treeby on "hi" http://www.k-wave.org/forum/topic/hi-1#post-4951 Thu, 22 Jan 2015 22:16:41 +0000 Bradley Treeby 4951@http://www.k-wave.org/forum/ Hi Mohsen, You can define the time step by setting <code>kgrid.t_array</code>. This is introduced in the <a href="http://www.k-wave.org/documentation/example_ivp_recording_particle_velocity.php">Recording The Particle Velocity Example</a>, and is also discussed in more detail in Section 3.2 of the k-Wave manual (page 30). Brad. mohsen on "hi" http://www.k-wave.org/forum/topic/hi-1#post-4941 Mon, 19 Jan 2015 12:28:13 +0000 mohsen 4941@http://www.k-wave.org/forum/ hello dr brad how could i change in step time value? our how much is step time value in above code? thanx bencox on "hi" http://www.k-wave.org/forum/topic/hi-1#post-4928 Mon, 05 Jan 2015 11:35:40 +0000 bencox 4928@http://www.k-wave.org/forum/ Hi mohsen, As the error message says, your <code>sensor.mask</code> is all zeros and k-Wave requires it to have at least one 1. If, for some reason, you don't want to use a sensor then just leave it out and run: <code>kspaceFirstOrder1D(kgrid, medium, source, []);</code>. Ben mohsen on "hi" http://www.k-wave.org/forum/topic/hi-1#post-4920 Tue, 23 Dec 2014 18:53:12 +0000 mohsen 4920@http://www.k-wave.org/forum/ hello brad I am trying to run this code % based on Heterogeneous Propagation Medium Example % 3rd April 2012 clear all; % create the computational grid Nx = 512; % number of grid points in the x (row) direction dx = 1e-3; % grid point spacing in the x direction [m] kgrid = makeGrid(Nx, dx); % define the properties of the propagation medium region1 = (kgrid.x > -Nx/3*dx) .* (kgrid.x < 0); region2 = (kgrid.x >= 0) .* (kgrid.x < 0.25*Nx/4*dx); medium.sound_speed = 1500*ones(Nx,1); % [m/s] medium.sound_speed(region1==1) = 2000; medium.sound_speed(region2==1) = 2200; medium.density = 1000*ones(Nx,1); % [kg/m^3] medium.density(region1==1) = 1500; medium.density(region2==1) = 1800; % define the initial pressure distribution mua = 10; p0 = exp(-mua*kgrid.x).*region2; source.p0 = p0; %define a sensor sensor.mask = zeros(Nx,1); % run the simulation sensor_data = kspaceFirstOrder1D(kgrid, medium, source, sensor); but i am encountered with this error !!! Error using kspaceFirstOrder_inputChecking (line 523) sensor.mask must be a binary grid with at least one element set to 1 Error in kspaceFirstOrder1D (line 433) kspaceFirstOrder_inputChecking; Error in k_wave_example_for_Mohsen_201412 (line 64) sensor_data = kspaceFirstOrder1D(kgrid, medium, source, sensor); what is its problem? thnx for your kindly guidance and merry chrismass best wishes Bradley Treeby on "hi" http://www.k-wave.org/forum/topic/hi-1#post-4917 Mon, 22 Dec 2014 14:16:44 +0000 Bradley Treeby 4917@http://www.k-wave.org/forum/ Hi mohsen, k-Wave uses a perfectly matched layer (PML) at the edges of the domain to simulate free field conditions, so you could consider a Sommerfeld radiation condition. "k-wave is divided(p(x,0)==0 --> p(x,0)^1/2=-p(x,0)^-1/2)" That's not quite right. k-Wave solves three first-order equations rather than the wave equation. This means it solves for acoustic pressure, density, and particle velocity. Because a time-staggered grid is used, odd symmetry is applied to the particle velocity (rather than the pressure) when using <code>source.p0</code> to ensure the particle velocity is zero at t = 0. k-Wave currently only includes models for wave propagation. If you want to model heat diffusion, you will need to solve the diffusion equation. Hope that helps, Brad. mohsen on "hi" http://www.k-wave.org/forum/topic/hi-1#post-4906 Tue, 16 Dec 2014 12:58:14 +0000 mohsen 4906@http://www.k-wave.org/forum/ brad i am solving this equation analytically too. indeed i will vallidated my method by k-wave toolbox. i was meaning about boundaru condition indeed, first and end points. what is considered in k-wave or what do i consider in my model. another thing initial value problem that is considered in k-wave is divided(p(x,0)==0 --> p(x,0)^1/2=-p(x,0)^-1/2).how about my model, should i make it like that? really i need help i am confused,so much. another thing, could i substitute coeficient cariable with temperature in k wave tool box? thank you so much mohsen on "hi" http://www.k-wave.org/forum/topic/hi-1#post-4905 Tue, 16 Dec 2014 12:49:34 +0000 mohsen 4905@http://www.k-wave.org/forum/ thnak you brad Bradley Treeby on "hi" http://www.k-wave.org/forum/topic/hi-1#post-4890 Fri, 12 Dec 2014 11:52:16 +0000 Bradley Treeby 4890@http://www.k-wave.org/forum/ Hi Mohsen, Do you mean the boundary conditions between the layers? In this case, both the acoustic pressure and the particle velocity normal to the surface must remain continuous across the boundary. You can already use k-Wave for modelling layered media. A good place to start is to work through the examples included in the toolbox, starting with the <a href="http://www.k-wave.org/documentation/k-wave_initial_value_problems.php">Initial Value Problems</a> (you can open these via the help browser in MATLAB). I'd also advise taking a look at the <a href="http://www.k-wave.org/documentation.php">k-Wave manual</a>. This includes a description of the source terms used in k-Wave. Brad. mohsen on "hi" http://www.k-wave.org/forum/topic/hi-1#post-4875 Fri, 05 Dec 2014 19:49:26 +0000 mohsen 4875@http://www.k-wave.org/forum/ tanx a lot for your nice guidances i am trying to solve a 1-D propagation of photoacustic wave in multi layers media analytically. firs i am too confused about my boundary conditions in first and end points. what B.C s should be used for my model. another thing is that how could i extend k-wave model for multi layer medias? my ultimate question, for photoacustic model what is considered source term in your model because it was not implied about derivative of heat equation that is source term of photoacustic wave. best mohsen