I have read that because turbulence has a fractal structure then all frequencies are excited equally and that makes the familiar whistling noise.
Is this explanation correct?
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asked May 3, 2021 at 11:57
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1$\begingroup$ What sort of whistling noise do you mean? Are you able to find a video on Youtube demonstrating the noise? $\endgroup$– NickCommented May 3, 2021 at 14:45
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1$\begingroup$ White noise is a pretty boring fractal. It's a bit like calling a straight line a fractal, since if you zoom in or zoom out it still looks like a straight line. $\endgroup$– AndrewCommented May 3, 2021 at 17:30
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1 Answer
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Turbulent air motion is excited by a fast train and hence acoustic power is radiated by that turbulent air as a "WHOOSH" sound. Because air has mass, elasticity and compliance, extremely low and extremely high frequencies might be missing from the actual sound spectrum of a fast train, but between those extremes all frequencies will be represented.
answered May 3, 2021 at 23:39
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$\begingroup$ The fact that all frequencies in a range are present does not mean that the noise is "white". It's more likely that the higher frequencies are less than the large ones at the injection scale because of turbulent cascade (red spectrum). $\endgroup$– QuilloCommented Feb 23, 2023 at 19:13