Preparing the Exhaust Geometry for Simulation

Use the tools in 3D-CAD to clean and prepare the exhaust pipe for simulation. These preparations include filling the end holes and closing up a gap.

  1. In the toolbar at the top of the 3D-CAD View scene, change (Color Mode) to (Distinguish Bodies).


Before repairing the geometry, check the validity of the parts. To run a validity check:
  1. Right-click the Exhaust Pipe node and select (Check Validity).
    A message with the results of the validity check is printed in the Output window. In this case, the following message is displayed: 
    All bodies of model are valid.
  2. Use the Fill Surface operation to close the inlets and outlets:
    1. In the Graphics window, select the edges that surround the first inlet.
      You can double-click a single free edge to automatically select all the free edges connected to it.


    2. Right-click one of the edges and select Fill Surface.
      The Fill Surface panel appears on the left of the Graphics window.
    3. In the Fill Surface panel, click OK.
      The inlet hole is filled with a surface.

    4. Repeat the steps above to fill the second inlet.
    5. Following the labels in the image below, rename the inlet faces to Inlet 1 and Inlet 2, respectively.


    6. Repeat the same process to fill the holes of the outlets. Rename the outlet faces to Outlet 1, Outlet 2, Outlet 3 and Outlet 4, according to the image below.


Use the Search tool to carry out a search on the entire geometry to find bodies that are interfering with one another.
  1. To search for bodies that are intersecting:
    1. Click (Show Filter) on the right side of the 3D-CAD View scene.
    2. Set Selection Mode to (Entire CAD model).
    3. Set Input Type to (Bodies).
    4. In the Search Criteria group box, create the following query:
      1. Select the Conditions option.
      2. Choose Clash + Body Pair + is + Interference. Click (Commit Changes).
    5. Click Search.
      The clashing bodies are displayed in the graphics window.
    6. Display the results in a table to identify which bodies are clashing:
      1. In the Results panel, next to Create, select Table and click OK.
        By default, the result table appears between the 3D-CAD simulation tree and 3D-CAD View scene.

      2. Close the table and, in the Design Filter 1: Input window, click Cancel.
    7. In the Vis toolbar, click (Save-Restore-Select Views) and select Views > -Y > Up +Z.
    8. If you zoom closely on Inlet 1, you can see that there is a gap between Body 1 and Body 3.


For this tutorial, you close the gap using the Bridge Surface tool. Because part of the surface of Body 1 intersects with Body 3, you must make planar cuts across Body 1 and Body 3. These cuts remove the overlapping surfaces and provides the Bridge Surface tool with uniform edges from which to grow the surface.
  1. To isolate the parts for repair, under the Body Groups node, multi-select Body 1 and Body 3, right-click and select Show Only.
  2. To slice Body 1:
    1. Right-click the edge of Body 1 (the short section of straight pipe) furthest from Body 3 and select Reference Geometry > Plane from Curve.
    2. In the Plane from Curve panel, set Type to Fitting Plane and click OK.


    3. In the feature tree, right-click Plane 1 and select Reference Geometry > Plane by Transformation.
    4. In the Plane by Transformation panel, enter -0.095 for the Z component of the Translation Vector and click OK.
    5. Expand the Body Groups node, right-click Body 1, and select Boolean > Slice.
    6. In the Slice panel, set the following parameters:
      Parameter Setting
      Keep Side Front Side
      Cutting Tools Plane 2
    7. Click OK.
  3. To slice Body 3:
    1. In the feature tree, right-click Plane 2 and select Reference Geometry > Plane by Transformation.
    2. In the Plane by Transformation panel, enter -0.0150 for the Z component of the Translation Vector and click OK.
    3. Expand the Body Groups node, right-click Body 3 and select Boolean > Slice.
    4. In the Slice panel, set the following parameters:
      Parameter Setting
      Keep Side Back Side
      Cutting Tools Plane 3
    5. Click OK.
  4. To close the gap:
    1. In the feature tree, multi-select Plane 1, Plane 2 and Plane 3.
    2. Right-click on the selection and select Hide.
    3. In the graphics window, multi-select the free edges on either side of the gap between Body 1 and Body 3.


    4. Right-click on the selection and select Bridge Surface.
    5. In the Bridge Surface panel, activate the following options:
      Bridge Surface Options
      Tangent to Faces for Source Edges
      Tangent to Faces for Target Edges
      Sew Bodies
      A preview of the operation is displayed in the 3D-CAD View scene.

    6. Click OK.
  5. Right-click a blank space in the 3D-CAD View scene and select Restore > Hidden Bodies.
The geometry is now ready and you can exit 3D-CAD.
  1. Click the Close 3D-CAD button at the bottom of the object tree.
    注The 3D-CAD View scene is closed automatically upon exiting 3D-CAD.
  2. Save the simulation.