Turbulent Sources

Turbulence generators (TGs) are used to force laminar to turbulent behavior of the boundary layer. They may be used to calibrate the turbulent boundary layer thickness in the wind-tunnel and force laminar-turbulent transition on flat surfaces.

Ground (Advanced)

When not using the “Standard” ground setup of full moving ground, the use of turbulence generators near the boundary layer suction region is recommended.

  1. From the Setup ribbon, click the Turbulence Source Tool.The
    Turbulence Source micro-dialog opens.
  2. From the viewer window, click on any part.
    A turbulence source is created and the Turbulence Source dialog opens.
  3. From Model Viewer > Turbulence Sources, click on the newly created Turbulence Source.
  4. From the Property Editor, set the General > Name value to Turbulence_Source_Ground to rename the newly created Turbulence Source.
  5. Set the Dimensions > Length, Width, and Height values to 7.477 m, 3.2 m, and 0.024 m respectively.
  6. Set the Zone Extents > X Min, Y Min, and Z Min values to -2.159 m, -1.608 m, and 0 m respectively.
  7. Deactivate Auto Calculate for Turbulence Parameters > > Eddie Length Scale and Turbulence Parameters > > Number of Eddies.
  8. Set Turbulence Parameters > Intensity, Eddie Length Scale, and Number of Eddies to 0.01, 0.012 m and 800 respectively.
  9. Close the Turbulence Source Tool by pressing on the green checkmark button on the Turbulence Source micro-dialog.
  10. Hide the Turbulence_Source_Ground part.
    Note: Parameter values specified for the ground turbulence source were calculated as per the ultraFluidX 2023.0 Setup guidelines for vehicle aerodynamics. This region is intended to accurately develop the boundary layer in the areas of the static ground near the vehicle downstream of the boundary layer suction.

Bulk (Optional)

For flat surfaces and certain smooth designs, the boundary layer might remain artificially pseudo-laminar. In such case, TGs may be added in the bulk and in front of the flat surface to force the laminar-turbulent transition and obtain a more realistic boundary layer development.

  1. From the Setup ribbon, click the Turbulence Source Tool.
    The Turbulence Source micro-dialog opens.
  2. From the viewer window, click on the hood of the vehicle.
    A turbulence source is created, and the Turbulence Source dialog opens.
  3. Click on the expand icon on the upper right corner of the Turbulence Source dialog to show the Length, Width, and Height fields.
    1. Set the Length, Width, and Height values to 1 m, 1.906 m, and 1 m respectively.
  4. Click on the hamburger menu on the upper right corner of the Turbulence Source dialog to expose additional parameters and set the value of Number of Eddies to 800.
  5. From Model Viewer > Turbulence Sources, click on the newly created Turbulence Source.
  6. From the Property Editor, set the General > Name value to Turbulence_Source_Front to rename the newly created Turbulence Source.
  7. Set the Zone Extents > X Min and Z Min values to -1.1 m and 0 m respectively.
  8. Close the Turbulence Source Tool by pressing on the green checkmark button on the Turbulence Source micro-dialog.
  9. Hide the Turbulence_Source_Front part.