Today’s invention is inspired by the idea of vortex flipping which is beautifully described here.
A fish, moving through water at medium speeds, sheds a vortex from one side of its body and then flips it to the other side of its body, using its tail. This shedding happens from right and left sides in sequence. The effect of this is to significantly lessen the drag force on the fish.
So, imagine say a streamlined vehicle, fitted with a tail device.
This tail can sense the motion of a vortex down its surface (perhaps by using whiskers protruding through the boundary layer) and, just as it is about to be shed, the tail moves to flick it to the opposite side of the vehicle.
This would have a measurable effect on fuel economy, as long as the roadspeed was not so high that the vortices became too small/fast to sense.
A back of the envelope calculation suggests that this drag reduction would only be significant at speeds less than about 10 MPH, so this is really only relevant to cyclists and mobility scooters.
