Processing results for acoustic analysis

To help you process results for acoustic and noise, vibration, and harshness (NVH) analyses, you can perform the following conversions through the Result Probe, Result, and Result Variable commands:

• Process vector results on frequency bands (frequency packing).

• Perform linear interpolation of results at specified frequencies or time.

• Project result vectors along the local normal.

• Convert order results to waterfall of frequency.

• Calculate normal acoustic intensity.

Processing of results on frequency bands (frequency packing)

You can use the group of Frequency Packing options in the Result Probe dialog box to create a new occurrence at the central frequency of each frequency band. The frequency packing options are available when Iteration Type is set to Frequency and the results are from a vibro-acoustic solution.

Four types of frequency bands are available:

• Octave

• 1/3 Octave

• 1/12 Octave

• Single Band — All the selected frequencies in a subcase belong to a single band. There is no central frequency for a single band.

The operations root mean square, root sum square, sum, and mean are available through the Combined Value of Bands list in the Result Probe dialog box.

For more information, see Octave bands.

Performing linear interpolation of results at specified frequencies or time

When you specify time or frequency values, you can use the Interpolation Option to perform linear interpolation of the results at the specified frequencies to find values at intermediate points. You can select a frequency form of linear or logarithmic sweep.

Three interpolation methods are available:

• Amplitude and phaseComputes the interpolated result value at given frequency or time using amplitude and phase.

• Real and imaginaryComputes the interpolated result value at given frequency or time using real and imaginary.

• Real and imaginary with unwrapped phaseComputes the interpolated result value at given frequency or time using real and imaginary with unwrapped phrase.

For more information, see Frequency interpolation methods.

Projecting result vectors along the local normal

When the result quantity is a vector, you can use the Display Result on Face Normal check box in the Result and Result Variable dialog boxes. When you select the check box, the software projects the selected vector result component (X, Y, Z, or Magnitude) along the local normal of each node. The software calculates the local normal of a node from its shared element face normal.

Converting order results to waterfall of frequency

When the results data in a result probe are order, you can use the Convert to Waterfall check box in the Result Probe dialog box to convert the results to rotational speed (RPM).

When you select the check box, the software extracts the rotational speed (RPMs) from the order values (either between specified values or for all values). The RPMs act as one independent variable. Combining across load cases (RPMs) produces a single value across the selected load cases.

If you do not select the check box to convert the order results, the software extracts the values for the order lines, and the order is the independent variable.

You can use the converted RPM values in the following ways:

• As a contour plot in a post view. The RPM value is displayed in the legend.Use the Next Mode/Iteration and Previous Mode/Iteration commands and the Result dialog box to step through the RPM values. If one RPM value has multiple frequencies, each increasing frequency value is shown before the next RPM value.

• As the X-axis of a graph. When you select to display the RPM values in a graph, a Frequency option is available from the X-Axis Defined By list in the Result Probe dialog box to display frequency values in the X-axis. The following graph shows displacements across frequency.

• As input to a field. When you select to use the RPM values in a field, the Table Field dialog box includes a column for the computed values for RPM.For order values, the Table Field dialog box displays a column for the order values.

Converting to acoustic normal intensity

You can define a formula for a result probe of acoustic results that calculates acoustic normal intensity at the time of evaluation using the AcousticIntensity() plug-in function. You enter the AcousticIntensity() plug-in function in the Formula box of the Result Probe dialog box.

You can also optionally specify:

• rho to specify the density of the fluid.

• c to specify the speed of light for different mediums, such as water.

For example:

AcousticIntensity(1000[kg/mm²],1500[m/s])

The software calculates acoustic normal intensity if displacement, velocity, or acceleration results exist. The preference for finding the results is Velocity > Displacement > Acceleration.

AcousticIntensity() uses the following formula to calculate acoustic normal intensity:

\prod \left ( f \right ) = \frac{1}{2}pcv^{2}(f)

where:

• Π(f) is the acoustic intensity (power flow per unit of normal area).

• ρ is the density of the fluid.

• c is the speed of sound.

• v(f) is the normal velocity.

To find the AcousticIntensity(rho, c) plug-in function in the Insert Function dialog box, set the category to CAEPluginSolutionDepend.

Where do I find it?

Create a result probe

Application	Pre/Post
Prerequisites	A Simulation file as the work part and the displayed partResults loaded
Command Finder	Result Probe

Create a result variable and convert result vectors to the local normal

Application	Pre/Post
Prerequisites	A Simulation file as the displayed part and work partResults loaded
Command Finder	Result Variables

Convert results vectors to the local normal

Application	Pre/Post
Prerequisites	Results loaded
Command Finder	Edit Post View
Location in dialog box	Post View dialog box→Result tab

How do I

Create a result variable to use in a result probe

Display results using a result probe

Output a result probe to a table field

Copy result probes

Delete result probes

Learn more

Result probes

Result variables

Generating result probe output

Using selection recipes with result probes

Look up more details

Octave bands

Frequency interpolation methods

Quick links

Command reference

Pre/Post video examples

Bulk Entry Descriptions

Simcenter 3D tutorials

Browse Simcenter 3D help by product area

Processing results for acoustic analysis, Simcenter 3D 2021.1 Series

© 2020 Siemens

window.mainLanguage="en_US"

window.delivId=""

window.projectId=""

MathJax.Hub.Config({ TeX: { extensions: ["autoload-all.js"] }, tex2jax: { displayMath: [ ] }, "SVG": { scale: 125 } });