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Unintersected Component Wireframes

This component of the Cart3D tutorial will walk through the process of generating an unintersected component wireframe in VSP and then using Cart3D's intersect utility to process the geometry into a single watertight body.

Although Cart3D's intersect tool is very robust, there are some cases it does not handle. One of these cases is when surfaces of two components are perfectly coincident. This situation occurs at the wing root of the Onera M6 model created in the tutorial; the root surface of the left and right wing halves are perfectly coincident.

One common fix for this situation would be to move the components slightly (say 10^-6) in the spanwise direction so the root surfaces are no longer coincident. Since the wing roots are normally buried inside a fuselage component, the gap between the wing halves would be insignificant. However, the Onera M6 geometry has no fuselage and any positive offset would result in a gap between the wings and any negative offset would result in intersection artifacts at the wing root. Furthermore, demonstrating the intersect tool with two components that don't really intersect is not very useful.

Consequently, for this part of the tutorial, a pod component will be added to the geometry to play the role of a fuselage in the model. This obviously would not be appropriate for matching the Onera M6 wind tunnel results, but it should do well for the purposes of this tutorial.

Generating an Unintersected Component Wireframe

  1. Onera M6 start
    • Start with the Onera M6 model from the end of the model building tutorial.
  2. Refine airfoil points
    • The triangulated wireframe is created by connecting the diagonals of the quadrilateral wireframe shown on screen. Consequently, the resolution of the triangulated wireframe is determined by the resolution of the quadrilateral wireframe shown on screen.
    1. In the 'Multi Sect Wing Geom' window, under the 'Gen' tab, enter 101 in the box to the right of 'Num Points:'
  3. Refine spanwise wireframe
    1. Select the 'Sect' tab and then click one of the right-facing arrows under 'Num Interpolated XSecs' until there are 40 interpolated cross sections.
  4. Add a pod

  5. Refine the pod

  6. Offset the wings

  7. Export

  8. Pick file

    • After export
    • Unintersected proof

Intersecting the Wireframe

Use the intersect tool.

Cart3D documentation

tutunint.1329363558.txt.gz · Last modified: 2018/04/01 14:40 (external edit)