Learning Forum

[z.aniretaj]

Hello!

I am trying to understand how the Reference PSD and Number of Divisions on Reference Sphere settings in DSF influence the amplitude of the incident waves. Based on the formula below, I understand that the amplitude depends on both the Reference PSD and the area of each segment on the reference sphere:

From the solver output and settings, I understand that Number of Divisions on Reference Sphere represents the number of parallel divisions on the sphere. My questions are as follows:

1. Does this parameter only divide the sphere into parallel rings (horizontal slices), or are there additional subdivisions to form segments (squares or rectangles)?
2. If there are additional subdivisions, how exactly are they defined geometrically?

Ultimately, I need to know the exact area of each segment because it directly affects the amplitude calculation. Knowing the segment area will allow me to adjust the Reference PSD to achieve a specific amplitude (for example, 1 Pa).
Correct me if I'm wrong in my reasoning. Maybe I misunderstood something.

I would appreciate any clarification or details about how the sphere is divided and how to interpret these settings.

Thank you!

[Erik Kostson]

Hi

I cannot provide detailed answers, but 

Normally we look at TL of plates when using that so the diffuse and transmitted energy is a ratio so does not really matter (incoming diffuse energy since it isa ratio), as TL is Energy/Power_diffuse_in/Energy/Power_transmitted .

See an example (APDL help manual) here on what we mean:

Acoustic Analysis Guide (APDL) . 13.15. Example: Structural Panel Subject to Excitation From a Diffuse Sound Field

This example problem demonstrates the use of the FLUID220 element to predict the transmission loss of a structural panel under excitation from a diffuse sound field.

All the best

Erik

[z.aniretaj]

Hi Erik

Thank you for your response!

1. Is DSF used exclusively for evaluating Transmission Loss (TL)?
2. What if I want to calculate the response of a body placed in a reverberation chamber? From what I understand, a diffuse sound field is created in such a chamber, correct? I would like to set the conditions to see how the body vibrates, and then compare those results with experimental data.
3. Does this mean I’m misunderstanding the kinds of problems where DSF can be applied?

Thank you in advance for your clarification!

[Erik Kostson]

Hi

No worries.

Can not say 100 % but that is the application we have an example on and that I have seen so far.

Not sure on what you are trying to do - never seen it used like this.

Perhaps someone else (forum member) has and can advice.

All the best

Erik

[z.aniretaj]

Sorry, I have one more question. So DSF is applied on a surface. Is there a way to see value of the pressure that is generated on this surface in results section?