Adjust Part Normals

Use the Normals tool to identify and correct the surface normal directions on parts.

The surface normals play an important role within the Aerodynamics and Aeroacoustics meshing process. In order for a model to be properly meshed, all surfaces in the model should have normal directions that point from solid to fluid. In other words, the normals must point outwards when viewing the model from the exterior. The normals also play an important role when identifying regions that are assigned as custom refinement zones, MRF volumes, and heat exchanger volumes. In each of these cases, the input to Aerodynamics and Aeroacoustics should form a closed volume and all normals should be oriented such that they point outwards from the enclosed volume.

Normals operations can be performed on a part or a region basis. A part is any collection of elements that you define as being grouped together. These will appear in the Model Browser as a single entry in the tree. A region is a collection of elements that are all connected to each other and grouped into a part. Parts can be made up of one or more regions. If there is more than one region in a part, there will be groups of elements that are not connected to each other. If you select Region when performing a Normals operation, only the elements that are connected to that region are affected and the rest of the elements in the part are left as is. If you select Part, all regions of the part are affected at the same time.

  1. From the Setup ribbon, click the Normals tool.

    Figure 1.
    Parts are colored according to their normal direction. Red indicates that the normals are pointing outward towards the viewing direction and blue indicates that the normals are pointing inwards.
  2. Reverse the normals on a part or region.
    1. Left-click on a part in the modeling window to reverse the direction of the normals.
      If the part consists of multiple regions, the view changes to isolate all regions of the part.
    2. Select whether an individual region should be reversed or the entire part should be reversed using the microdialog.
  3. Find and repair parts with mixed normal directions.
    A part with a mixed normal direction is defined as a part in which there are adjacent elements with opposite normal directions. This situation is typically undesirable and could lead to spurious results.
    1. Click Find Mixed on the guide bar to locate parts with conflicting normals.
    2. Click or to cycle through mixed parts.
    3. Left-click on a part in the modeling window.
    4. If your selection requires it, choose whether to reverse the region or the part using the microdialog.
    5. Click Unify All on the guide bar to unify all regions of all parts.
Tip: Use window selection to highlight multiple parts.

Keyboard Shortcuts & Mouse Controls

To do this Press
Adjust element normals in the selected isolated region Shift + Left Mouse Click