Air or water flowing attaches to the nearest surface. In this demo, blowing air over a curved surface causes lift.
This effect can cause a circular winged aircraft to lift off.
Next, we find a way to make the fan quiet. Go for the minimum power needed. A bigger, slower fan will produce the same flow with less noise. Mount fans so vibration isn’t transmitted and amplified. Most of our current technology is clumsy and loud. But the solution to a noiseless powerful efficient fan exists in nature.
Fish don’t leave much of a wake when they swim because the snakelike motion causes the water to follow the surface of their bodies and guides the water from a large disturbance into a small one using the Coanda effect. A fish tail is very thin at the end for this reason.
The fish tail pushes the water to get thrust but the snake motion then pulls the water back toward the place it was. The taper of the tail makes the water exit the fish with little disturbance. With minimal vortices of air, water or any fluid created my movement, the sound and drag is reduced. Minimize drag and you maximize thrust.