system
Given the following post, respond as if you're commenting on Reddit:
human
Using biology to reduce drag

In theory, would I be able to reduce drag using 'fish scale' like coverings? Particularly towards the rear of a vehicle? Would strategically placed 'scales' be able to reduce drag (possibly, like a golf ball's dimples?) or additionally increase downforce?



Additionally, would mechanized scales, able to be computer controlled and moved effectively, improve handling, reduce drag, increase downforce, and counter other aerodynamic forces? Completely impractical, but in theory would it be aerodynamically useful?
gpt
(Mech. Engineering)

At the rear of the vehicle, a zone of low pressure is created because air is forced to move into the space left by the vehicle.  Because the air impinging on the front of the vehicle is at higher pressure, this creates a net force on the vehicle, which is a major component of drag.  Adding things like fish scales, dimples, ect... towards the rear of the vehicle would thicken the boundary layer of air (air moving more or less with the vehicle) around the area the scales or other protrusions cover.  Although for some specific cases this might have a net positive effect on vehicle performance, there is no universal mechanism for why this would be a good thing.

On the front of the vehicle, however, there could potentially be a benefit from boundary-layer thickening by adding dimples, small protrusions, ect if that increase in the boundary layer helps make airflow over a sharp discontinuity in the vehicle's shape (junction between windshield and hood in some cars, ect...) flow more smoothly.  This might help eliminate some frictional drag on the vehicle itself or possibly help maintain a smoother flow of air over the vehicle, which might prevent the formation of energy-wasting vortices, ect....

However, whenever possible, smooth, generally teardrop shaped vehicles are best.  Fish scales are mostly a protective coating to keep parasites out and assist fish in maintaining an different osmotic balance inside their bodies than in the water they live in.  Also have you ever handled a fish?  Most fish who do a lot of swimming have sleek, smooth-to-the-touch bodies.