I was recently involved in a project where we were investigating the physics of tibetan singing bowls. We discovered that when the bowl was filled with a sufficiently effervescent fluid, the bowl would not 'sing' or resonate at all. We termed this 'effervescent damping' but we have no idea how it actually takes place. Note that this type of damping did not occur with any of the non-fizzy liquids of similar viscosity and density.

No one we asked seemed to know the reason. Any help help in explaining this would be appreciated.

We also later found a paper stating that wine-glass playing (a similar idea to singing bowls) was not possible when the wine glasses were filled with champagne.

  • $\begingroup$ I would hazard a guess that its because of the disolved gas in the form of bubbles adding additional damping with a different coefficient than the fluid. But that is just a guess and I hope someone comes by to answer it because i am curious as well. $\endgroup$ – Triatticus Jun 24 '18 at 3:15
  • 1
    $\begingroup$ Seems that the rapid adiabatic compression and decompression of tiny gas bubbles in the liquid at the frequency of the sound wave could conceivably be a significant energy damping mechanism since the temperature of the gas in the bubbles increases during adiabatic compression, and some of that thermal energy is lost during each oscillation cycle to the surrounding liquid due to thermal conduction. Would require some time and effort to sit down with a paper and pencil and work out an estimate of how big of an effect that is, though. $\endgroup$ – user93237 Jun 24 '18 at 4:15

For a singing bowl with water in it to resonate will require the mass of the water to be coupled to the mass of the bowl walls. This means there will be standing pressure waves within the fluid when the bowl is at resonance.

Within a 3-D standing wave in a body of fluid there will be regions where the pressure in the fluid goes slightly negative (and others where the pressure is slightly positive) relative to atmospheric. If you exert a slight amount of negative pressure on a fluid which is supersaturated with dissolved gas (like freshly-opened club soda for example) it tends to exsolve the gas in those regions, performing a little work on the fluid/gas system in the process. The performance of that work extracts energy from the standing wave, damping it.

In this sense, exsolvation of dissolved gas in regions of slightly-negative pressure within the fluid would suppress the establishment of standing waves in the fluid, which is probably the reason why your bowls could not resonate with soda water in them.

This could be tested experimentally by using a xenon flash strobe system to illuminate the fluid in the bowl for photography. The experiment is begun with pure water and the bowl set into resonance. The strobe is then sync'ed to that resonance. Then you slowly inject a syringeful of club soda into the center of the bowl and look for regions where the water turns milky, suggesting the transient exsolvation of the gas in regions of negative pressure.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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