Vortex shedding frequency depends on flow speed and wire size, not wire tension

Evidence

For a piano wire of diameter 2 mm and a wind speed of 10 kph, the frequency f is around 300 Hz. The vortex shedding is not wire vibration— it is airflow around the wire that is oscillating even if the wire is perfectly still. (The formula, equation 14.1, for the frequency f does not involve the tension in the wire.) However, suppose the tension of the wire is adjusted to make one of the wire vibrational mode frequencies correspond to the vortex shedding freequency. The side-to-side wagging of the air directly behind the wire exerts two oscillating forces on it: One is called the lift force and oscillates perpendicular to the flow, with a period given by the period of vortex shedding (two vortices per period). The other force points along the direction of wind: a drag force. The drag force has a steady component and a component that acts at twice the frequency of the lift force, because the drag force is the same every time either a right or a left vortex is about to shed, which is half of the vortex shedding period. — Eric J. Heller, Why You Hear What You Hear- An…, 1291

Categorization

• DEFINE: Clearly separates vortex shedding (an airflow phenomenon independent of the wire’s tension) from wire vibration, and distinguishes the lift force (perpendicular, fundamental frequency) from the drag force (along-flow, at double frequency).