Trouble with Error: ambiguous flow-through subsurface detected

[Jasper]

Dear OpenVSP Team,

I am trying to use the wave drag tool, however my engine ducts (inlet and outlet) are giving an error when doing the wave drag analysis: Error: ambiguous flow-through subsurface detected. I have done the line subsurface for the inlet face and the same for the outlet, as was highlighted in the workshop tutorial and in previous threads. So I am not sure what im doing wrong, perhaps the geometry is too aggressive and thus not water tight or because the inlets are intersecting with the fuselage, but im not at all sure. It was highlighted in the Integrated Flowpath Modeling workshop that the wave drag tool does not yet work with the engine definition in the fuselage geometry, hence why im adding the subsurfaces.

I have attached the design below. While it still meshes the engine duct geometry, it unfortunately does not subtract it and give the errror message.

[Brandon Litherland]

I'm having trouble opening this model and pulling up Wave Drag.  No error messages are popping up but when this model and wave drag are open at the same time, VSP crashes without fail.  Not sure what's going on.  Let me step back a few versions and see if I can find where it breaks.

[Brandon Litherland]

Model fails to open in 3.47 or 3.46. I'll keep looking.

[Brandon Litherland]

Got it to work by inserting the VSP3 file into a fresh 3.48.2 version new model.  Weird.

Anyway, as you note, Wave Drag doesn't work with the engine definitions.  If you turn your mode back to None (Geom Type) you'll see a lot of self intersecting loops and bends in the surface.  My suggestion is to first recreate your engine ducts from scratch without using engine definition parameters.  Once you have that, then try using the subsurface method to identify inlet and outlet regions which should extend fore and aft to cut the intersected surfaces.