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Sound Barrier

Here we will perform a 2D simulations concerning wave propagation over a sound barrier.

Thereby the wave is excited by a point source on the right side of the barrier in the origin [x,y,z]=(0,0,0) of the domain.

For the analysis type, we chose a harmonic analysis in the frequency range of 34Hz to 680Hz with 10 linearly spaced samples.

Since we cannot create an infinitely large computational domain, we have to impose a model of free-radiation, in this example, we are using the PML (Perfectly Matched Layer) technique, described here.



As a preprocessor we use the free available software gmsh

The gmsh file is provided here and the mesh can be generated by executing

gmsh geometry.geo -2 -v 0 -format msh2 -o geometry.msh

XML Simulation Setup

The ready-to-use xml file is provided here as well as the material xml file.

Here, we will just discuss the main parts of the XML description file (for a deeper introduction into the different analysis types, we refer to the Cantilever example)

  • Domains with regions
<domain geometryType="plane">
    <region material="air" name="prop"/>
    <region material="air" name="plate"/>
    <region material="air" name="pml"/>
    <nodes name="excite">
      <coord x="0.0" y="0.0" z="0.0"/>
  • Start the sequence and define analysis
      <numFreq> 10 </numFreq>
      <startFreq> 34 </startFreq>
      <stopFreq> 680 </stopFreq>
  • Define PDE for acoustics
        <region name="prop"/>
        <region name="pml" dampingId="myPml"/>
  • Define the PML (Perfectly Matched Layer) used for free field radiation
      <pml id="myPml">
        <type> inverseDist </type>
  • Define excitation and output result
      <pressure value="1" name="excite"/>
      <nodeResult type="acouPressure">

Perform the openCFS simulation by executing

cfs simulation


You can now investigate the results in paraview