Setting Up a Post FW-H Simulation

The key steps in the setup of a Post FW-H simulation are the definition of the FW-H Surfaces, the import of the .simh file as CAE model, the definition of the Post FW-H receivers, and the execution of the Post FW-H solver.

Before you run a Post FW-H simulation, you are advised to run an unsteady simulation for noise sources in the near-field using the recommended aeroacoustics analysis procedure.

To set up a Post FW-H simulation:

  1. Add the Post FW-H model to your simulation.
    See Post FW-H Model Reference.
  2. Create the Post FW-H surfaces:
    1. Right-click the Post FW-H Surfaces node and, depending on the type of surface, select New > Post Permeable Surface or Post Impermeable Surface, respectively.
    2. Select the Post FW-H Surfaces > [post FW-H surface] node and set Boundaries to the boundaries or surface derived parts that define the sources of noise.
      For permeable FW-H surfaces, make sure that the surface normals of the selected interface boundaries or surface derived parts are pointing inwards (that is, opposite the direction of sound propagation).
      To check the surface normal direction:
      1. In a vector scene, plot the Area field function on both boundaries of the interface or on the surface derived part.
      2. If the surface normal does not point inwards, do one of the following:
        • For interface boundaries, select the other side of the interface as source boundary.
        • For surface derived parts, select the derived part, then activate Flip Orientation.
      See Post FW-H Surface Reference.
    3. To create multiple Post FW-H surfaces, repeat Steps 2 a and b as required.
  3. Set up the Post FW-H solver:
    1. Select the Solvers > Post FW-H Solver node.
    2. Set the following properties:
      • Start Time Step—the time-step of the first data export event.
      • Collection Frequency—the number of time-steps between export events.
      • Base Name—the name of the .simh file to which the data is exported.
      • Export Directory—the directory to which the .simh file is written. Set a directory that has adequate space for writing the solution history file.
      See Post FW-H Solver Reference.
  4. Run the simulation.
    Simcenter STAR-CCM+ automatically creates a Solution Histories > [base name] node and writes a [base name].simh file to the export directory.
    The mesh is written to the .simh file just once, at the specified start time step. The coordinates of rotating meshes are not written—the coordinates are transformed internally.
    During the run, surface data are written to the .simh file at the specified collection frequency.
  5. When the simulation completes, create a CAE model based on the data stored in the .simh file:
    1. Right-click the Solution Views > [base name] node and select Create Static CAE Model from Recorded Parts.
      A CAE model is created under Imported Models as follows:
      • simh:[base name]
      • Imported Surfaces
      • [region]: [boundary 1]
      • [region]: [boundary 2]
      • ...
      • Mapped Source Data
      • Update
      where the imported surfaces are created from the mesh that was exported to the .simh file at the specified start time step.
      Under Regions, Simcenter STAR-CCM+ creates a corresponding region that is based on geometrical elements detected in the .simh file.
      The CAE model node provides an interface to the exported .simh file. After the import process, the imported CAE model nodes are connected to the corresponding region nodes.
    2. Select the Mapped Source Data node and make sure that the properties are set as follows:
      PropertySetting
      Source SurfacesThe surfaces from the .simh file (read only).
      RepresentationThe representation of the solution view from which you created the CAE model.
      FunctionsThe field functions from the .simh file, such as [Pressure, Density, Velocity].
      Interpolation MethodThe interpolation method that is used for mapping the data. The following options are available:
    3. Select the Mapped Source Data > Update node and make sure that the properties are set as follows:
      PropertySetting
      EnabledActivated
      TriggerTime Step
  6. Create the Post FW-H receivers:
    1. Create a point probe and set the following properties:
      PropertySetting
      Input PartsSelect all imported FW-H surfaces located under Imported Models > simh:[base name] > Imported Surfaces.
      [X, Y, Z]Specify the far-field position where you want to receive acoustic data.
    2. Right-click the Post FW-H Receivers node and select New.
    3. Select the Post FW-H Receivers > [post FW-H receiver] node and set the following properties:
      PropertySetting
      Point PartSelect the created point probe.
      Imported FW-H SurfacesSelect the imported FW-H surfaces from which you want to capture sound.
      See Post FW-H Receiver Reference.
    4. To visualize the receiver, open a scene, then select the Post FW-H Receivers > [post FW-H receiver] node.
      The receiver is highlighted in the scene.
    5. To create multiple receivers, repeat Steps 6a - c as required.
  7. Run the Post FW-H solver:
    1. Right-click the Solvers > Post FW-H Solver node and select Execute Solver.
    2. In the Reset Transient Display Time? dialog, click Yes.
    The solver automatically maps the field data between the CAE model surfaces and the boundary faces and computes the sound pressure at the receivers. The results are stored for each receiver in table format under Post FW-H Receivers > [post FW-H receiver] > [post FW-H receiver table].
  8. Analyze the results, for example:
    • Visualize and animate the mapped pressure:
      1. Create a scalar scene and set the following properties:
        Node Property Setting
        [scalar scene]
        Scalar 1 Representation Volume Mesh
        Parts Parts Select all imported surfaces, such as:

        Imported Models > simh:[base name] > Imported Surfaces > [region]: [boundary 1] and [region]: [boundary 2]
        Scalar Field Function MappedPressure
      2. Select the Imported Models > > simh:[base name] > Mapped Source Data > Update node and set Trigger to Update Event.
      3. Select the Update > Event Frequency node and set Update Event to [State Change : [base name]].
      4. Right-click the Solution Views > [base name] node and select Animation > Play.
    • Plot the sound pressure surface total versus acoustic time:
      1. Create an XY Plot.
      2. Expand the plot node, right-click Data Series, and select Add Data.
      3. In the Add Data Provider to Plot dialog, expand the Post FW-H Receivers > [post FW-H receiver] node and select the relevant [post FW-H receiver table] node.

      Alternatively, you can create a new plot and then drag the [post FW-H receiver table] node onto the plot window.

    • Create a data set function:
      1. Right-click the Tools > Data Set Function > G(p) 1 > Tabular node and select New derived data from table.

        A new node appears under Tabular.

      2. Select the Tabular > [data derived from a table] node and set the following properties:
        Property Setting
        Input Data 1 Post FW-H Receivers > [post FW-H receiver] > [post FW-H receiver table]
        X Column 1 Acoustic Time
        Y Column 1 Sound Pressure Surface Total
        Update Activate Activated
  9. If you want to modify a receiver—for example, if you want to position the receiver at a different location, you can edit the receiver properties and then execute the Post FW-H solver again.
For practical examples of Post FW-H simulations, refer to the following tutorials: