Extracting the Internal Volume

Before extracting the internal volume, use the Dynamic Sectioning tool to visually inspect the parts for gaps. Once you have identified the gaps in the geometry, use the extend solid tool to close them.

Right-click a blank area in the 3D-CAD View scene and select Restore Hidden Bodies.
Use the Dynamic Sectioning tool to visually inspect the geometry:
1. In the toolbar at the top of the 3D-CAD View scene, click Display Cut Parts using Multiple Planes.
2. In the Dynamic Sectioning panel, select ZX Plane, set Offset to 0.03 and deselect all the options for Section 2.
3. Click Close.
4. In the Vis toolbar, click (Save-Restore-Select Views) and select Views > -Y > Up -Z.
5. If you zoom closely towards the resonator part, you will notice gaps between the body and its connecting parts.
6. Use the dynamic sectioning tool to visually inspect the remaining parts. You will notice that there are gaps between each connecting parts.
  The image below shows where the gaps are present in the geometry.
Use the Split Faces tool to project the edge of the tail pipe onto the resonator:
1. Zoom in closely towards the gap and select the edge of the tail pipe that lies above the face of the resonator, as shown in the image below.
2. Right-click on the selected edge and select Repair Tools > Split Faces By Edge Projection.
3. In the graphics window, select the face of the resonator that is positioned below the edge.
4. In the Split Faces panel, set Max Projection Distance to 2.0 mm and click OK.
5. Repeat the steps above to include the edges and faces as shown in the image below.
6. Repeat the steps above to project the edge from the connecting pipe onto the muffler. For this operation, in the Split Faces panel, set Max Projection Distance to 3.0 mm.
Use the Extend Solid tool to fill the gaps:
1. Zoom in closely to visualise the gap between the resonator body and its connecting parts.
2. Select the face under the tail pipe, as shown in the image below.
3. Right-click on the selected face and select Extend Solid.
4. In the Extend Solid panel, set Method to Up To Face and select the face above it for Target Face.
5. Click OK.
6. Repeat the steps above for the remaining gaps.

Once you have filled all the gaps, you use the extract internal volume to create a fluid volume.

To carry out an internal volume extraction:
1. In the toolbar at the top of the 3D-CAD View scene, select the (Toggle Section View) icon to deactivate the dynamic sectioning scene.
2. At the bottom of the 3D-CAD View scene, select the (Face Feature) menu and select Extract Internal Volume.
3. Click the (Object Selector) icon on the right of the Enclosing Bodies box.
4. In the Object Selection panel, select all the bodies, then click the icon again when done.
5. To hide the color of the enclosing bodies, right-click inside the Enclosing Bodies box and select Hide on scene.
6. Click within the Inlet/outlet Edges or Faces box and select the following faces:
  - The inlet face of the resonator
  - The outlet faces of both exhaust tips
  Once you have selected the faces, normally a preview of the solid body appears in the 3D-CAD View scene when an internal volume is found. For this case, the preview is not shown which indicates that there might be a leak in the geometry. To identify leaks:
7. Switch the Extraction Mode to (Detect Leaks and Extract Liner).
8. In the 3D-CAD View scene, follow the leak path to the muffler.
9. In the graphics window, zoom in closely towards the leak, then hold the CTRL key and select the edge of the hole.
  The image below shows the leak path to the muffler and if you zoom in closely you will find the leak hole.
  
  When no further leaks are detected, a yellow preview of the solid body is shown in the scene.
10. Switch the Extraction Mode to (Extract Internal Volume).
11. Click OK to proceed with the volume extraction.
Multi-select all the new feature nodes, then right-click on the selected features and select Group.
Rename the feature group to Extracting Internal Volume.
Save the simulation.