Acoustic Analysis

anmolk
anmolk Altair Community Member
edited March 2021 in Community Q&A

Hi

I am trying to analyze the noise heard by the passenger inside the cabin (of vehicle) due to some external acoustic source as well as base excitation due to road.

I am using NVH application with Optistruct solver. I am able to analyze the base excitation due to road.

But I am not sure how to perform the analysis for noise generated by a far field source.

To be more precise how can I create acoustic cavity mesh for fluid outside the cabin and define acoustic source. (Acoustic cavity tab asks only to select structure components and seat components).

 

Thanks

Anmol

 

 

 

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Answers

  • anmolk
    anmolk Altair Community Member
    edited March 2018

     

    I found the method in this thread. but I am wondering how can I define CACINF4 element type for only outermost elements because I need to specify grid points in definition.

    Is there a way to extract element connectivity table for the faces or some other way please let me know?

    Thanks

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited March 2018

    Hi,

     

    You can extract faces, move to a different component and change the element type to CACINF4

     

  • anmolk
    anmolk Altair Community Member
    edited March 2018

    Okay Thanks. For now I just made a very simple planar ambient field instead of sphere just to verify. I am getting same error as described in previous thread, ' *** ERROR 1684: FLUID element  1736620 points to non-fluid GRID 210175.'

    I see that for some grids cd = -1. How do I resolve this. These grids lie inside the vehicle cavity.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited March 2018

    Hi @anmolk

     

    To resolve this issue you need to card edit all the fluid grids and choose CD= -1 for them. (This has to be done for all the nodes except the constrained node). You can card edit all the fluid grids at the same time. 

  • anmolk
    anmolk Altair Community Member
    edited April 2018

    Appreciate your help that worked.

    I have couple of questions though about this procedure.

    1. I ran the analysis for low frequency ranges <200Hz. Is it valid for higher frequencies as well f=1-2kHz? If it is how may I improve the accuracy?

    2. Can I use infinite elements approach to analyze noise inside Composites structures as well?

    Please let me know

     

    Thanks

     

  • Subash Karthikeyan
    Subash Karthikeyan New Altair Community Member
    edited March 2021

    Hi anmolk,

    I'm planning to do the same kind of analysis where i want to analysis the noise levels outside of a cabin,

    can u help on me that.

    It will be hepful

    Regards & Thanks

    Subash K

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