http://www.k-wave.org/forum/topic/asymmetrical-velocity-vector Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 00:22:35 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/asymmetrical-velocity-vector#post-971 Sat, 03 Nov 2012 01:59:54 +0000 Bradley Treeby 971@http://www.k-wave.org/forum/ <p>Hi Erik,</p> <p>The offsets you see are due to the staggered grid scheme that is used in k-Wave (you can find some more details <a href="http://asadl.org/jasa/resource/1/jasman/v111/i1/p53_s1">here</a>). In 2D, the x-components of the particle velocity are calculated at positions (x + dx/2, y), and the y-components are calculated at positions (x, y + dy/2). If you want an estimate of the particle velocity on the non-staggered grid points, one approach would be to record the values at two neighbouring points and use interpolation. </p> <p>Hope that helps,</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/asymmetrical-velocity-vector#post-960 Thu, 01 Nov 2012 15:45:26 +0000 styxed 960@http://www.k-wave.org/forum/ <p>Hello,</p> <p>I have a problem working in 2D with the <code>&#39;ReturnVelocity&#39;</code> option.<br /> I have a single source point at <code>(x,y)</code> with a certain <code>source.p0</code>. Two sensor points are placed at <code>(x, y-d)</code> and <code>(x, y+d)</code> with d=10 or whatever.</p> <p>As expected, the pressure in the two sensor points are exactly the same. Since the setup has been made symmetrically, I would also want the velocity vector in the y-direction to be the same (but opposite). But they are not, because I think the velocity at point <code>(X, Y)</code> is calculated with the difference in pressure between points <code>(X, Y)</code> and <code>(X+1, Y)</code> (for <code>sensor_data.ux</code>), right?. For example the velocity vector at <code>(x, y-d)</code> and <code>(x, y+d-1)</code> &lt;b&gt;are&lt;/b&gt; the same.<br /> Is there a 'neat solution' for this issue by for example using the pressure in points <code>(X-1, Y)</code> and <code>(X+1, Y)</code> in kspaceFirstOrder2D?</p> <p>Erik </p>