ATV sets

Acoustic Transfer Vectors (ATVs) let you efficiently compute vibro-acoustic pressure at microphones. 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. ATVs are only available in vibro-acoustic analyses.

When you use the SOL 108 Acoustic Transfer Vector solution 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.

Using an ATV in your vibro-acoustic analyses results in faster computations of a vibro-acoustic model than a traditional model of a structure coupled to an acoustic fluid. ATVs are efficient when analyzing large models over many frequencies, or rotational speeds, because the ATV needs to be computed only once, but then you can reuse it 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.

(1) Acoustically radiating structure, (2) Microphone or microphone mesh, (3) Acoustic Transfer Vectors representing the fluid exterior to the acoustically radiating structure

Using an ATV in your vibro-acoustic analyses is a two-step process:

1. You first compute the ATV using SOL 108 Acoustic Transfer Vector solution. During this step, the software writes the ATV matrices to an xxx_atv.op2 file.

2. Then you use the computed ATV in SOL 108 or SOL 111 solutions to solve the acoustic response in an assembly FEM by changing the fluid domain to an ATV set.

You can use the solved ATVs for multiple vibro-acoustic solutions, provided that the boundary of the structure to the fluid does not change. Variations of the structure can include:

• Materials

• Interior structural details

• Loads

• Operating RPM or frequency

How do I

Replace different FEM files with an ATV set or VATV set

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ATV set workflow

ATV set in assembly FEM workflow

Plot mode, ATV, or VATV set contours

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ATV sets, Simcenter 3D 2021.1 Series

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