http://www.k-wave.org/forum/topic/artifact-pattern-chevron-like-in-2d-and-3d-k-wave-simulation-with-linear-arr Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 21:40:19 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/artifact-pattern-chevron-like-in-2d-and-3d-k-wave-simulation-with-linear-arr#post-9241 Thu, 16 Oct 2025 16:39:01 +0000 amadou 9241@http://www.k-wave.org/forum/ <p>Dear k-Wave team,</p> <p>I’m currently running a 2D simulation using kspaceFirstOrder2DG to model ultrasound propagation of a plane wave at 0° from a linear array source in water (L11-5), and I’m observing a strong “chevron-like” interference pattern in the reference medium (homogeneous water).<br /> This pattern looks like crossed diagonal bands, even though the medium is fully homogeneous.I define the sources using karraysources class. My grid size is 1/15 of the wavelengt</p> <p>The same simulation were also conducted in 3D considering probe elevation of 5 mm and using kwave_transducer. </p> <p>If the simulatios are run with a kerf (both 2D and 3D) of some grid points, the issue is amplificated and the artifacts become stronger. At lower frequencies, these artifacts are still present but at a smaller scale. </p> <p> Here are the main parameters of my setup:</p> <p>fc = 7.6e6; % Central frequency<br /> c_water = 1540; % Sound speed in water<br /> rho_water = 1000; % Density<br /> ppw = 15; % Points per wavelength<br /> dx = floor((c_water/fc/ppw)*1e5)*1e-5;<br /> dy = dx;</p> <p>N_elements = 64;<br /> pitch_m = 300e-6;<br /> elem_width_m = pitch_m;<br /> ix_probe = round(1e-3/dx)+1;<br /> tone_burst_cycles=3;<br /> win = hanning(N_elements);<br /> source_signal = toneBurst(1/kgrid.dt, fc, tone_burst_cycles);</p> <p>PML_size = 30;<br /> PML_alpha =4; % higher values were also used but no change<br /> cfl = 0.15;</p> <p>`<br /> The transducer and sensor are both linear arrays located at ix_probe (which is 1mm away from the boundary).<br /> I’m running two simulations (one with scatterers, one reference), then subtracting their pressure fields.<br /> However, even in the reference case (homogeneous water), I see this strong interference pattern (see attached figure).</p> <p>My questions are:</p> <p> Is this interference pattern expected given my pitch (300 µm) and frequency (7.6 MHz)?</p> <p> Could it be a spatial aliasing or grating-lobe effect related to the array discretization?</p> <p> Are there recommended values for pitch, element_width, or PML parameters to avoid these artifacts in k-Wave 2D simulations?</p> <p> Would reducing the pitch below λ/2 or adjusting the apodization help mitigate this?</p> <p>Any insight or guidance on proper transducer discretization or grid setup to avoid this pattern would be greatly appreciated.</p> <p>Best regards,</p> <p>Amadou </p>