Box Cavity for a pick-up truck

[kach22i]

Originally Posted by Sven7

Might be related:
Semi Boat Tail & Box Cavity Patent

(Includes several illustrations)

Figure-13, the stepped boxes is quite an interesting approach.

[aerohead]

Originally Posted by Sven7

Might be related:
Semi Boat Tail & Box Cavity Patent

(Includes several illustrations)

Continuum's was very similar,excepting that their's also had a bottom panel.
That's an amazing link! You can definitely see how so many have been motivated to find the magic-bullet for big rigs.

[aerohead]

in the center of the right hand column you can see the reduced wake beyond the step of the box cavity

Here you can see the captured-vortex which spans the length of the cavities steps

The position and dimension of these rearward facing steps is critical to the effectiveness of the cavity.

[freebeard]

If the box was a rectangular bellmouth instead of a straight section the outer face would offer a return for the toroidal vortex. And alter the s/Lr ratio.

Then when you go to a stepped box, it could all collapse like a folding camper's cup.