Distributed Acoustic Plane Waves loading for indirect acoustic and vibro-acoustic analyses (Acoustics BEM)

Acoustics BEM supports applying a diffuse acoustic field loading of a panel or structure. You can accomplish this using the new Distributed Acoustic Plane Wave load type and the new Random Subcase–Distributed Acoustic Plane Waves solution step for a random vibro-acoustic analysis.

Internally, when the solver processes the Distributed Acoustic Plane Wave load in the Random Subcase—Distributed Acoustic Plane Waves solution step, it creates several uncorrelated load cases containing plane waves, and combines the results of each load case to compute power spectral density (PSD) or cross spectral density (CSD) random acoustic responses due to the diffuse acoustic field loading. A typical application in which this type of diffuse field load is applied is the virtual acoustic loading of a spacecraft with a strong acoustic diffuse field.

To use random loading in your model, you must first create a Random Subcase–Distributed Acoustic Plane Waves solution step. Then, you define the Distributed Acoustic Plane Wave random load in that solution step. You can create only one random subcase in the same solution.

Random loading

You use the Distributed Acoustic Plane Wave random load to define an acoustic field that impacts the model with a given pressure amplitude as the load. The distributed acoustic plane wave load is composed of a set of plane waves that create a diffuse field. You can apply sets of acoustic loads to your mode in a pattern, such as a sphere or hemisphere around the fluid domain.

Distributed Acoustic Plane Waves Display (full sphere)	Distributed Acoustic Plane Waves Display (hemisphere)

Modeling objects

• For indirect BEM vibro-acoustic analyses, you can define the following modeling objects:Vibration PSD Selection to request vibration power spectral density (PSD) results.Vibration CSD Selection to request vibration cross spectral density (CSD) results.

• For indirect BEM acoustic and indirect BEM vibro-acoustic analyses, you can define the following modeling objects:Pressure PSD Selection to request pressure power spectral density results.Pressure CSD Selection to request pressure cross spectral density results.

Output requests

You can request the following outputs:

• For structural vibration results:SORT1 PSD (displacement, velocity, or acceleration)SORT2 PSD or CSD (displacement, velocity, or acceleration)

• For acoustic pressure results:SORT1 PSDSORT2 PSD or CSD

Plot results

You can plot the following results (displacement, velocity, acceleration, or pressure) in scenario-based post-processing:

• Nodal results

• Frequency-dependent PSD results

• Frequency-dependent CSD results

• RMS results

For more information, see Scenario-based post-processing.

Where do I find it?

Creating distributed acoustic plane waves

Application	Pre/Post
Prerequisites	A Simulation file as the work part and displayed partSimcenter 3D Acoustics BEM as the specified solverIndirect Acoustic or Indirect Vibro-Acoustic as the specified analysis typeSubcase Random - Distributed Acoustic Plane Waves as the specified solution step
Simulation Navigator	Expand the Random Subcase- Distributed Acoustic Plane Waves solution step node of an active solution→right-click the Loads container→New Load→Distributed Acoustic Plane Waves

Creating vibration PSD/CSD selection or pressure PSD/CSD selection modeling objects

Application	Pre/Post
Prerequisites	A Simulation file as the work part and displayed partSimcenter 3D Acoustics BEM as the specified solverIndirect Acoustic or Indirect Vibro-Acoustic as the specified analysis type
Command Finder	Modeling Objects
Location in dialog box	Modeling Objects Manager dialog box→Type list→

Creating random indirect BEM acoustic or random indirect BEM vibro-acoustic output requests

Application	Pre/Post
Prerequisites	A Simulation file as the work part and displayed partSimcenter 3D Acoustics BEM as the specified solverIndirect Acoustic or Indirect Vibro-Acoustic as the specified analysis type
Simulation Navigator	Expand the Solution node of an active solution→right-click Random Subcase-Distributed Acoustic Plane Wave subcase→Edit
Location in dialog box	Solution Step dialog box→Output Requestslist→Random IBEM Acoustic Output Requests or Random IBEM Vibro-Acoustic Output Requests→Create Modeling Object

How do I

Define forcing frequencies (Acoustics BEM)

Learn more

Boundary conditions (Acoustics BEM)

Defining acoustic sources and loads (Acoustics BEM)

Assigning frequencies from all loads to subcases

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Command reference

Pre/Post video examples

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Distributed Acoustic Plane Waves loading for indirect acoustic and vibro-acoustic analyses (Acoustics BEM), Simcenter 3D 2021.1 Series

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