I want to improve aerodynamic performance of a recumbent tailbox by smoothing the airflow around rider and reattaching it to tailbox by an enshrouding duct using Coandä effect - to forcibly channel the air against the tailbox to “make it stick” and provide pressure recovery for reduced drag without the need for a full fairing (which is hardly practicable).
Here is a VERY rough model:
My mockup model (admittedly, a mess) is getting rejected by the mesher, so I’ve created a very simple proof of concept model using simple geometric shapes - because I have NASA data with Cd values.
Here is my link to the project:
Unfortunately, the air seem to refuse to “stick” to tailbox, though I did get some improvement in Cd.
Does the system model Coandä effect at all, or I should make some adjustements? Making the system much larger/more complex would defeat its entire purpose and I’ll be better off with a full fairing perhaps.
Of course, current “state of the art” dictate a tailbox that is a bit larger that the body and use that space to smooth the transition from body to tailbox, but it increases frontal area, I thought ducting will do the same…
Turbulence develops with flow speed. Laminar flow is omnipresent and knowing which shapes allow for longer laminar flow is useful. Humans try to eliminate turbulence in their devices, but dragonflies know better! They use turbulence to master their magic fly in all directions. This is a small weekend digression… 