Aeolian tones

Among the Äolstönen (also Aeolstöne ) are meant those tones that result from flow around a cylindrical body.

They were already described by Athanasius Kircher in 1650 and systematically examined by Vincent Strouhal in 1878 . Strouhal found that there is a relationship between the pitch (i.e. the sound frequency ) and the cylinder diameter and its flow velocity : ${\displaystyle f}$ ${\displaystyle d}$ ${\displaystyle v}$

${\displaystyle f\sim {\frac {v}{d}}}$.

As a constant of proportionality, Strouhal introduced the constant : ${\displaystyle c}$

${\displaystyle f=c\cdot {\frac {v}{d}}}$.

The constant of proportionality is later called Strouhal's number in honor of Strouhal . The Strouhal number, as it turned out in later studies, is not constant, but depends on the viscosity and density of the medium that flows around the cylinder. ${\displaystyle c}$

etymology

As with the Aeolian harp , the name Aeolus is derived from Aiolos (Latin: Aeolus), the ruler of the winds in Greek mythology.

Individual evidence

1. ↑ Peter Költzsch On the history of flow acoustics ( Memento of the original from June 22, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. 
2. ^ V. Strouhal: About a special kind of excitation of the sound. Annalen der Physik und Chemie, Leipzig 241 (5) (1878) 10, pp. 216-251