[aerohead]

Originally Posted by Tesla

Starting with a typical vehicle cross section, rectangle/hexagon/squircle type of shape in most cases, how do we transition to a simpler semicircular aeroform to work with?

Are we guided by the points that lag most on vehicle according to template, these would be the corners where roof and sides meet or can we average the transition and assume the air where transition is slower will move across to fill area where transition is faster.

I'm looking at a vehicle to trailer canopy situation.
I've done a bit of a chart to help visualise it.

The outer black shape represents the vehicle shape at rear
The smaller black shape represents where the shape would be according to template at 4' from vehicle.
The red ellipse is the start of trailer canopy and the other ellipses represent sections along length of trailer canopy.

The areas shaded orange are where the ellipse shape has transitioned faster then template, whilst the rest of ellipse is slower then template.

Can we safely assume that the air from these areas would travel across as indicated by arrows to fill void where transition is faster, thus avoiding the vorticies that can form off the corners?

Is it as simple as comparing and balancing the area differences under the respective curves?

Edit: Freudian slip in title, it may well end up being a camper trailer, so "bedding" may be involved.

I believe that it is about area.Or 'sectional density' which is associated with it,which NASA's Richard Whitcomb worked with.
You'd take the variance in cross-sectional area at any position along a template,then alter your station bulkhead at that location as it morphs away from the original section shape in a way to maintain an identical sectional area.
The volume of air displaced at that position remains constant,although where the displacement occurs is varying.