5
$\begingroup$

You can obviously hear wind. From everyday experience, the stronger the wind, the louder its sound. But this sound is always similar, and quite distinctive, noise-like. Can one compute the spectrum of the noise generated by the wind?

There is an inkling of an answer provided here: "Any way, once the wind starts doing non-linear things, it can generate periodic stresses, and from that you get the whistling or humming noise we all know and love." Could anyone expand on this, or provide references with more quantitative detail?

Improve this question
$\endgroup$
3
  • $\begingroup$ It depends what it's blowing through - trees, whatever. Anyway, it's "white" noise. $\endgroup$
    – Mike Dunlavey
    Feb 25, 2016 at 20:01
  • 1
    $\begingroup$ @MikeDunlavey it's quite definitely not white. That's why it sounds different depending on speed. $\endgroup$
    – Carl Witthoft
    Feb 25, 2016 at 20:36
  • $\begingroup$ @Carl: That's why I said "white" :) $\endgroup$
    – Mike Dunlavey
    Feb 25, 2016 at 21:34

1 Answer 1

Reset to default
4
$\begingroup$

I would recommend you to study Howe's Theory of Vortex Sound. Generally, an appearance of vorticity $\omega$ leads to conversion of a tiny part of flow kinetic energy in a pressure wave (really small part: proportional to $M^5$ in a free field). The main free field source is the divergence of the Lamb vector:

$$ \frac{1}{c_0^2}\frac{\partial^2 p}{\partial t^2}-\Delta p = \rho_0 \ \mathrm{div} (\omega \times v) $$

It's obvious that the maths is not very nice and complicated vorticity field in turbulent flows leads to noise-like perception of the generated sound.

Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.