Steady state fluid velocity in an acoustic solution workflow

You can use a steady state fluid velocity in an acoustic solution to simulate air flow over a vehicle or air flow generated by a turbine or propeller.

Performing a Simcenter Nastran acoustic solution with the effects of fluid velocity is a two-step process. To create the solution, do the following:

1. Create a Model and Load Pre-Processing solution.

2. Create a Simcenter Nastran Acoustic SOL108 Direct Frequency Response solution and include a Convection Flow Velocity simulation object.

Step	Summary	Detailed help topic
Potential Flow Solution
1.	Open or create a Simulation file	Create or open a Simulation file using the Simcenter Nastran Acoustic simulation template.	Create a new Simulation fileCreate a Simulation file using the Simcenter Nastran Acoustic simulation template.
2.	On the Acoustics and Vibration tab, select Potential Flow.	Do one of the following:In the Simulation Navigator, right-click the Simulation file and choose New Solution Process→Model and Load Pre-processing .Choose Acoustics and Vibration tab→Model and Load Pre-processing .
3.	Create boundary conditions at the inlet and outlet.	In the Simulation Navigator, right-click the solution process and choose Add Load→ Input File.
4.	Open the input velocity file.	In the Input File dialog box, click Browse to navigate to and select a steady state velocity (CGNS) file.Click Refresh to populate the Data.
5.	Deselect all but velocity data.	Double-click a quantity (such as Mass Density or Temperature) to deselect the data.Note: Only Velocity data is valid in this application.
6.	Load the intermediary mesh to provide velocity mapping to your fluid mesh.	In the Simulation Navigator, under the solution process node, right-click the input file and choose Load Intermediary Mesh.Note: The Transient Mesh is displayed on your fluid mesh and each mesh is listed in the Simulation Navigator.
7.	Add mesh mapping from the CGNS data.	In the Simulation Navigator, right-click the solution process and choose Add Operation→Mesh Mapping.	Mesh Mapping dialog box
8.	Select the source mesh type.	In the Mesh Mapping dialog box, in the Source Mesh group, select Stationary.In the Options group, select Transfer Data.The Mesh Mapping node is displayed in the Simulation Navigator.
9.	Complete the mesh mapping.	In the Simulation Navigator, under the mesh mapping node, right-click the mesh mapping data and choose Edit.
10.	Set parameters for mesh mapping.	In the Mesh Mapping Data dialog box, in the Name box, type a name for the data set.In the Mesh Mapping group, do the following:From the Mapping Method list, select Maximum Distance.In the Number of Influencing Nodes box, type 8.Set the Maximum Distance to encompass the entire fluid mesh.In the Transfer From group, select Intermediary Entities.In the Transfer To group, select Model Entities.Note: Leave the Mesh Mapping Data dialog box open.
11.	Select the velocity source mesh.	In the Transfer From group, click Select Source .On the Top Border bar, do the following:From the Type Filter list, select Transient Mesh Group.From the Selection Scope list, select Within Work Part and Components.
12.	Select the velocity source mesh.	Select the source mesh from the graphics window or the Simulation Navigator.
13.	Select the destination mesh.	In the Simulation Navigator deselect (hide) your intermediary mesh and select the fluid mesh.In the Transfer To group, click Select Model .On the Top Border bar, do the following:From the Type Filter list, select Element.From the Selection Scope list, select Within Work Part and Components.In the graphics window, select all elements by dragging a selection box around them.
14.	Validate the mesh mapping.	Right-click the solution process and choose Validate.Note: Examine the Information window for any errors. If there are zero errors the mapping has been validated. Close the Information window.
15.	Solve the solution process.	Right-click the solution process and choose Solve.When the Model and Load Pre-processing Solve dialog box appears, click OK.
16.	Use Post-Processing Scenario to examine the results.	Right-click the solution process and choose Post-Processing Scenario.	Scenario-based post-processing

Step	Summary	Detailed help topic
SOL108 Direct Frequency Response Solution workflow
1.	Create a SOL108 Direct Frequency Response Solution.	In the Simulation Navigator, right-click the Simulation file and choose New Solution.In the Solution dialog box, do the following:Enter a name for the solution.From the Solver list, select Simcenter Nastran.From the Analysis Type list, select Acoustic.From the Solution Type list, select SOL108 Direct Frequency Response.Click Create Solution.
2.	Edit the Case Control to select output.	In the Solution dialog box, on the Case Control page, click Create Modeling Object (next to Output Requests).In the Acoustic Output Requests dialog box, do the following:Enter a name for the output request.In the Properties group, click Disable All.Enable the following output requests:Acoustic IntensityAcoustic Particle VelocityAcoustic PowerAcoustic PressureDuct Modes (Transmission Coefficients and Transmission Loss)Click OK to close the Acoustic Output Requests dialog box.	Acoustic Output Requests and Vibro-Acoustic Output Requests dialog boxes (Simcenter Nastran).
3.	Edit the Bulk Data to enable FEMAO.	In the Solution dialog box, on the Bulk Data page, select the Enable Adaptive Order for Acoustic Elements check box.Click OK to close the Solution dialog box.
4.	Create the subcase.	In the Simulation Navigator, right-click the solution and choose New Subcase.In the Solution Step dialog box, do the following:Enter a name for the subcase.From the Step list, select Subcase - Specific Duct Modes.Click Create Step.Click OK.
5.	Create a duct mode load.	In the Simulation Navigator, under the Subcase node, right-click the Loads container and choose New Load→Specific Duct Mode to create the desired duct mode load.	Creating duct modes workflow
6.	Create convection flow velocity.	In the Simulation Navigator, under the solution, node, right click Simulation Objects and choose New Simulation Object→Convection Flow Velocity.In the Convection Flow Velocity dialog box, open the CGNS file to import the Convection Flow Velocity solution results.In the Data Source group, select Infer Data Sets to enable VELOCITY.	Convection Flow Velocity dialog box
7.	Create other New Simulation Objects as needed.	Add simulation objects to completely define the acoustic solution.Acoustic AbsorberAutomatically Matched LayerTransfer AdmittanceAnechoic End DuctAcoustic Temperature MappingNote: Acoustic Continuity is not available.	Acoustic Absorber dialog boxAutomatically Matched Layer dialog boxTransfer Admittance dialog box (Simcenter Nastran)Specific Duct Mode / Distributed Duct Mode / Anechoic End dialog boxAcoustic Temperature Mapping dialog box
8.	Create microphone mesh.	Create a microphone mesh to measure sound inside or outside the acoustic fluid.	Create microphones
9.	For the solution edit the advanced solver options.	Edit the Advanced Solver Options. Set the units to:(Force)(Length)(Mass) = (N)(m)(kg)Specify Temperature Unit = Kelvin	Solve dialog boxExport Simulation/Advanced Solver Options dialog box—Nastran
10.	Solve the solution.	Solve the solution to compute the analysis results.	Solve the model
11.	Post-process the results with Post-Processing Scenario to examine the results.	Right-click the solution Results and choose Post-Processing Scenario.	Create contour plotsScaling acoustic results

Learn more

Finite Element Method Adaptive Order (FEMAO) solutions

Solution stabilization options

FEMAO convected flow workflow

Using viscoelastic materials in FEMAO solutions

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Steady state fluid velocity in an acoustic solution workflow, Simcenter 3D 2021.1 Series

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