Visualizing the Sound Pressure Level at Different Frequencies

The solution history file can be used in a fast Fourier transform to visualize the sound pressure level on the stored surfaces at selected frequencies.

To visualize the sound pressure level at different frequencies:
  1. Right-click the Tools > Data Set Functions node and select New > Surface Time History (h[s]).
  2. Select the h(s) 1 node and set the following properties:
    Property Setting
    Start Signal 0.02 s
    End Signal 0.0533 s
  3. Right-click the h(s) 1 > Imported node and select New derived data from surface.
  4. Select the Multi-Point Time History node and set the following properties:
    Property Setting
    Representation cylinderPressureData
    Data Surfaces 1
    • Regions > Body 1 > Boundaries > Cylinderwall
    • Derived Parts > Plane Section
    Target Surfaces
    • Regions > Body 1 > Boundaries > Cylinderwall
    • Derived Parts > Plane Section
    Field Function 1 Pressure
    Update Active Enabled
  5. Right-click the Data Set Functions node and select New > Surface Time Fourier Transform (G[h[s]]).
  6. Select the G(s) 1 node and set the following properties:
    Property Setting
    Analysis Blocks 2
    Overlap Factor 0.5
    Start Signal 0.02 s
    End Signal 0.0533 s
    Window Function Hann
  7. Right-click the G(s) 1 > Imported node and select New derived data from derived data.
  8. Expand the Multi-Point FFT node and set the following properties:
    Node Property Setting
    Multi-Point FFT Input Time History Multi-Point Time History
    Update Active Activated
    Output Control Frequency Mode Frequency
    Output Field Sound Pressure Level
    Display slider control Slider Value 500
  9. Create a scalar scene, rename it to Sound Pressure Level, and set the following properties:
    Node Property Setting
    Sound Pressure Level
    Outline 1
    Parts Parts Parts > Body 1
    Scalar 1 Contour Style Smooth Filled
    Parts Parts Derived Data > Multi-Point FFT
    Scalar Field Function Derived Data > Multi-Point FFT


    The SPL (dB) values at the top and bottom of the cylinder exactly match the point spectra dB levels at 500 Hz.

  10. To view the sound pressure level at a different frequency, select the Multi-Point FFT > Display slider control node and set Slider Value to the frequency of interest.
  11. Save the simulation.