ATV sets (Acoustics BEM)

BEM Acoustic Transfer Vectors (ATVs) let you efficiently compute vibro-acoustic pressure at locations of microphones in interior or exterior problems. An ATV is a simplified representation of an acoustic fluid that interacts by one-way (weak) coupling of a vibrating structure with an acoustic fluid.

When you use the Acoustic Transfer Vector solution in the Simcenter 3D Acoustics BEM environment to calculate an ATV, the solver computes the pressure caused by the unit normal surface volume velocity of each acoustic boundary node. The solver then computes resulting pressures at specified microphones for the frequencies that you select, and it uses those results to accurately interpolate for intermediate frequencies, computing results for the complete frequency range.

The use of an ATV in your vibro-acoustic analysis results in faster computation of your vibro-acoustic model than a traditional model of a structure coupled to an acoustic fluid. ATVs are efficient when you analyze large models over many frequencies or rotational speeds because the ATV only needs to be computed once. You can then reuse the ATV many times to examine changes in your model such as structural materials, loads, and so on.

As a best practice, you compute ATVs between the minimum and maximum frequencies of your frequency range of interest using appropriate frequency intervals for external or internal cavities. So that you can reuse the ATV in all of your intended scenarios, ensure that this frequency range is large enough. When you use an ATV as a vibro-acoustic component representation, the ATV responses are interpolated between your excitation frequencies. ATV responses above or below the vibro-acoustic excitation frequency range are not extrapolated or computed.

• When the ATV represents the fluid exterior to an acoustically radiating object, you can use large frequency intervals between the minimum and maximum frequencies. In an exterior acoustic problem, the ATV evolves smoothly through the frequency range, and thus ATVs are well suited for this case.

• When the ATV represents the fluid inside acoustic cavities, the ATV must model acoustic cavity resonances. To accurately account for the cavity resonances, the frequency intervals should be smaller than the frequency intervals used for exterior acoustic solutions.

To use a BEM ATV in your vibro-acoustic analysis, do the following:

1. Request the software to calculate an ATV of a model that contains 2D acoustic fluid and microphone meshes in an indirect acoustic analysis using the Acoustic Transfer Vector solution in the Simcenter 3D Acoustics BEM environment.

2. Use the computed ATV and one of the following:A mode set in a vibro-acoustic Modal Acoustic Transfer (MATV) Response solution of the Simcenter 3D Noise and Vibration environment.Enforced motion loads (displacements, velocities, or accelerations) in the frequency domain from an external file in a vibro-acoustic ATV Response solution of the Simcenter 3D Noise and Vibration environment.

Note:

The Acoustic Transfer Vector solution supports the following simulation objects:

• Infinite Plane

• Acoustic Absorber

• Transfer Admittance

Where do I find it?

Creating ATV solutions

Application	Pre/Post
Prerequisites	A Simulation file as the work part and displayed partA FEM or assembly FEM file that contains 2D acoustic fluid and microphone meshesSimcenter 3D Acoustics BEM as the specified solverIndirect Acoustic as the specified analysis typeAcoustic Transfer Vector as the specified solution type
Command Finder	Solution
Simulation Navigator	Right-click the Simulation file→New Solution

Creating an ATV Set

Application	Pre/Post
Prerequisites	A Simulation file as the work part and displayed partA FEM or assembly FEM file that contains 2D acoustic fluid and microphone meshes, and one of the following depending on the solution type:Simcenter 3D Acoustics BEM as the specified solverIndirect Acoustic as the specified analysis typeAcoustic Transfer Vector as the specified solution typeA solved Acoustic Transfer Vector solution
Command Finder	ATV Set

Replacing FEM component with ATV Set

Application	Pre/Post
Prerequisites	A Simulation file as the work part and displayed partSimcenter 3D Noise and Vibration as the specified solverVibro-Acoustic as the specified analysis typeMode set (Modal Acoustic Transfer (MATV) Response solution)Enforced motion loads from an external file (ATV Response solution)
Simulation Navigator	Right-click the FEM or assembly FEM file→Edit Representation→ATV Set→select an ATV set from the Acoustic Transfer Vector Set list

How do I

Replace different FEM files with an Acoustics BEM ATV set

Plot BEM ATV contours

Learn more

ATV set workflow (Acoustics BEM)

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ATV sets (Acoustics BEM), Simcenter 3D 2021.1 Series

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