Air exiting bell

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elmsandr
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Re: Air exiting bell

Post by elmsandr » Tue Jul 21, 2020 7:08 am

Basbasun wrote:
Tue Jul 21, 2020 3:11 am
https://www.youtube.com/watch?v=xyoGz5P ... p8oVBpQqew
This is a good demonstation of the subject. The air flow from the bell is very slow.
Does airspeed matter with respect to viral transmission?

Cheers,
Andy
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JohnL
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Re: Air exiting bell

Post by JohnL » Tue Jul 21, 2020 7:16 am

elmsandr wrote:
Tue Jul 21, 2020 7:08 am
Does airspeed matter with respect to viral transmission?
I would think that it relates to how far virus material will travel, particularly larger droplets.
brumpone
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Re: Air exiting bell

Post by brumpone » Wed Aug 05, 2020 1:32 pm

An organisation in the UK just released some results they hope will inform government policy: https://www.bbe.org.uk/news/04082020-16 ... ch-results
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BGuttman
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Re: Air exiting bell

Post by BGuttman » Wed Aug 05, 2020 4:41 pm

That's a great study. The one thing we need to determine yet is how relatively contagious aerosols are versus droplets. I'm pretty sure there is a difference.
Bruce Guttman
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RoscoTrombone
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Re: Air exiting bell

Post by RoscoTrombone » Thu Aug 06, 2020 2:08 am

I've just read this with great interest and the covers look like a potential win in the short term but I'm wondering how they affect the sound?

I also see you can get them for wind instruments too which is great however the poor old flute loses out again. I wonder what the experiment would show there?
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BGuttman
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Re: Air exiting bell

Post by BGuttman » Thu Aug 06, 2020 7:49 am

Much more air goes over the flute than through it (I'm talking a transverse flute here; not a recorder). When playing the flute you are projecting the droplets a lot. Probably only exceeded by sneezing.
Bruce Guttman
Merrimack Valley Philharmonic Orchestra
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Oslide
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Re: Air exiting bell

Post by Oslide » Fri Oct 23, 2020 8:51 am

I don't know whether this is the appropriate thread to cite this article because it's not directly related to "air exiting the bell", but it's a new study about the transmission of airborne droplets and aerosols, and as such may be of interest to readers of this thread, and beyond.

S. Balachandar et al.
Host-to-host airborne transmission as a multiphase flow problem for science-based social distance guidelines.

Full article here: https://www.sciencedirect.com/science/a ... 2220305498
Ceterum censeo to fetch All of TTF
CharlieB
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Re: Air exiting bell

Post by CharlieB » Fri Oct 23, 2020 12:09 pm

https://www.sciencedirect.com/science/a ... 2220305498
A classic example of how to kill a fly with a sledgehammer.
I questioned who would pay for such a complicated analysis of how far a sneeze droplet travels.
These guys........
International Journal of Multiphase Flow
https://www.elsevier.com/journals/inter ... ss-options
Well, they don't actually pay. They charge a fee for others to post on their site.
Must be a Covid effect.......scientists and engineers with way too much free time on their hands

Maybe we should challenge one of these guys to design a trombone with partials that stack perfectly with no slide adjustment. That should keep 'em busy for awhile.
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BGuttman
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Re: Air exiting bell

Post by BGuttman » Fri Oct 23, 2020 12:56 pm

Sorry, air flow and acoustics are two entirely different fields, especially at the PhD level.

There are now multiphysics programs (Comsol, CFD) that can make analysis of air flow with or without droplets relatively easy.

I don't think anybody has yet harnessed the multiphysics programs to musical instrument tone production, but if anybody has it's probably Yamaha.
Bruce Guttman
Merrimack Valley Philharmonic Orchestra
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CharlieB
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Re: Air exiting bell

Post by CharlieB » Sat Oct 24, 2020 9:03 am

Bruce, I think you took my comment too literally. I probably should have phrased it differently.
It was intended to be a jibe at those in our (engineering) profession who make simple problems unnecessarily complicated.
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