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How can i get transmission loss considering damping in harmonic acoustics?

- November 21, 2023 at 12:16 pm
  SANG JUN LEE
  Subscriber
  I'm designing helmholtz resonators (silencer) and using harmonic acoustics to check how much noise of which frequency is reduced by the resonator. but when i check the transmission loss, i see large peak only at certain frequencies. However, i know that in reality, a smooth graph is created over a wide range. I think the reason why such a prominent peak appears is because damping is not considered when the air vibrates. Can damping be used in acoustics analysis?
- November 21, 2023 at 12:52 pm
  
  Erik Kostson
  Ansys Employee
  
  Hi
  
  You can include the viscosity that adds some acoustic damping to the acoustic domain – this might be enough.
  Often it might not be enough to capture the correct behaviour though. So the Helmholtz resonace frequency is captured by FEA acoustics, but the amount of transmission loss predicted is too small. This is because there might be some losses that can not be accounted for with FEA acoustics.
  All the best
  Erik
  - November 22, 2023 at 5:06 am
    
    SANG JUN LEE
    Subscriber
    
    Thank you!
    Then, how can i put viscosity effect when i analyze in harmonic acoustics?
- November 22, 2023 at 5:34 am
  
  Erik Kostson
  Ansys Employee
  
  Hi
  Viscosity is a material property, and is thus defined in Engineering Data (ED).
  If you use our defualt material such Air or Water Liquid from our ED general material libray it is allready defined.
  All the best
  Erik

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