# Enclosed Cavity Acoustics

Member

I am using ANSYS 2020 R1. I am trying to compute the sound pressure inside a thin walled 6 sided steel box. I want to excite one side of the box with a force and compute the sound pressure inside the box. Can anyone tell me the general setup for this and boundary conditions. Does ANSYS view this an FSI problem, a harmonic acoustics problem or other? I have tried to setup the 6 sided box in modal and then harmonic response and then transfer this load to Harmonic acoustics but it doesnt seem to be working. Any suggestions or links to helpful tutorials would be greatly appreciated. Thanks.

• Member
edited November 16

There are many videos around which you can look at.

A relevant one is this:

Hope this helps

You could also have a full FSI vibro-acoustic analysis and not a velocity import load transfer to the air like in the video.

We would then have a harmonic acoustic with both fluid and structure inside (see below, 2 regions, acoustics for fluid/gas, and physics for the structure), and then run that:

• Member

Thanks. I have watched this video a couple of times. It doesnt do an enclosed field. I am needing to have the 6 sides of the rectangular enclosure interact with the air and the air excite the walls. Do you know of any videos that show this?

• Member

In your message you are doing a Modal Acoustics. Do I want to do a Modal Acoustics or a Harmonic Acoustics? What do I use for a boundary condition on the air? Thanks for the help.

• Member

This was just an example to show the setup when we do a full fsi vibro-acoustic analysis.

So if you have a harmonic excitation, and want to look at the vibro-acoustic response, then we can use a harmonic acoustic response (modal calculates the modes, but not the response under excitation).

In order to provide some more guidance we would need to see an inline image of your geometry showing the air domains and the solid structure, the excitation you want to have, and what you want to analyse and predict.

So much more information would be of help to us and so we can provide some feedback.

Thank you

Erik

• Member

Erik,

My domain is a six sided rectangular box. Its a box made of thin steel plates. The inside of the box is the acoustic cavity. I want to excite one of the plates with a force and have compute the sound pressure in the box. Then I need the vibrating air to excite the other plates. I need the plates to interact with the air and the air to interact with the sides of the box.

I need to measure the sound pressure in the air due to the sides of the totally enclosed box vibrating.

Can you give me some help? Thanks