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flow5 uses the sub-structure of FACEs to build the connections between the wings and the fuselage. It is important that this set of FACEs is as simplified as possible to facilitate meshing operations, e.g.:
The BEM requires that the plane and wings be merged in one or more closed non-intersecting volumes.
To achieve this, the fuselage needs to be hollowed out were they connect. This is achieved using OCC's boolean operators.
The detailed process to assemble the plane is described here [link].
Only the uncut shapes are stored in the project file. The cut geometries are meant to be meshed immediately after the boolean operation and are discarded when the project is unloaded.
A project file with examples of fuselages imported from STEP files generated by OpenVSP can be downloaded here: STEP_fuse.fl5
The fuselage model used for this tutorial is the one from the P51D Mustang project (http://hangar.openvsp.org/vspfiles/420). The fuselage has been exported as a STEP file using VSP's default settings.
Fuselage objects are imported using the Insert menu in the plane editor.
To create the SHELL and eventually fix the topological shapes, open the fuselage editor by clicking on the three dots in the right "Action" column.
The fuselage will not appear in the 3d views until the SHELL(s) have been built.
In the editor, click on the button "Fix shapes" to open the shape fixer interface.
Click on the "Stitch shapes" button. This will launch the sewing of FACEs.
Click OK to save the change and exit the interface. The fuselage should now appear in the 3d view.
Open again the shape fixer interface, and click this time on the button "Reverse shapes". The output shows that the topological orientation has been reversed, meaning in this case that the normal is now pointing outwards.
Click "OK" to save the change.
To verify the orientations of the surface elements, display the "Normals" in the 3d view and make sure that they point outwards.
--- For versions >= v7.01 beta 16 only -----
If a SOLID has been successfully built, then it is likely that there are no gaps in the topology. As an extra precaution, it is possible to verify the absence of free edges in the mesh.
Make sure that the node coincidence distance is suited to the element size. Typically this distance should be 0.1 mm. Triangle vertices closer than this length will be considered identical.
Connect the elements using the option in the "Actions" menu. This is a necessary step since a free edge is identified as an edge belonging to only one triangle.
Finally, request a "Check free edges". None should be found.