[kach22i]

Kármán vortex street
https://en.wikipedia.org/wiki/K%C3%A..._vortex_street


Drag of a Sphere
https://www.grc.nasa.gov/www/k-12/ai...ragsphere.html

Case 3 shows the flow as velocity is increased. The downstream vortices become unstable, separate from the body and are alternately shed downstream. The wake is very wide and generates a large amount of drag. The alternate shedding is called the Karman vortex street. Here is a computer animation of the shedding, with the flow going from right to left.

This type of flow is periodic, it is unsteady but repeats itself at some time interval. The pressure variation associated with the velocity changes produces a sound called an aeolian tone. This is the sound you hear when the wind blows over high-power wires or past tree limbs in the fall or winter. It is a low frequency (low pitch), haunting tone.

The Audi White Noise Concept Is an Electric Vehicle With a Snarl
https://hypebeast.com/2016/4/audi-white-noise-concept

We’re all for environmentally-conscious design, but who doesn’t prefer the distinct vroom of a gasoline-powered vehicle over the dull hum of an electric engine? Frederic Allenberg is looking to offer the best of both worlds with his Audi concept. Dubbed the White Noise, the sleek, minimalist production doesn’t employ the artificial audio of other designs. Instead, there’s a reason for the vehicle futuristic, sculptural form. Thanks to its aerodynamic shape and chassis fins, the White Noise takes cues from the Aerolian Harp and is able to take advantage of fluid dynamics and the Kármán vortex street to funnel air between cables that are attached to the lower body of the car. The result? A natural tone that has more in common with the R8 than a Prius.

Though just in concept form for now, the technology could be employed by and tailored to any vehicle as the sound can be modified at will by changing the number of cables, their length or tension.

Source
Yanko Design