Do bubbles heat up as they collapse?

[KingNothing]

In the video at http://www.spikedhumor.com/articles/108195/Real_Life_Creature_Assassin.html

they say something about the "bubbles momentarily reach the temperature of the sun". I don't understand this bit at all, or how this mechanism works.

 

[FredGarvin]

If you're referring to cavitation bubbles, it can increase in temperature quite a bit. Here is a great on-line reference for bubble dynamics and cavitation:

When a cavitation bubble grows from a small nucleus to many times its original size, the collapse will begin at a maximum radius, RM, with a partial pressure of gas, pGM, which is very small indeed. In a typical cavitating flow RM is of the order of 100 times the original nuclei size, Ro. Consequently, if the original partial pressure of gas in the nucleus was about 1 bar the value of pGM at the start of collapse would be about 10-6 bar. If the typical pressure depression in the flow yields a value for (p∞*-p∞(0)) of, say, 0.1 bar it would follow from Equation 2.38 that the maximum pressure generated would be about 1010 bar and the maximum temperature would be 4×104 times the ambient temperature! Many factors, including the diffusion of gas from the liquid into the bubble and the effect of liquid compressibility, mitigate this result. Nevertheless, the calculation illustrates the potential for the generation of high pressures and temperatures during collapse and the potential for the generation of shock waves and noise.

http://caltechbook.library.caltech.edu/1/04/chap3.htm#L1

Here is the TOC of the book:
http://caltechbook.library.caltech.edu/1/04/content.htm

This is a highly specialized field of study. I won't pretend to know anything except the very elemental aspects so I can't get into the deep physics of what is going on.

 

[AlephZero]

The surface temperature of the sun is about 5800 degK i.e. about 20 times the ambient surface temperature of the earth, so FredGarvin's factor of "4x10^4 times the ambient temperature" is more than enough to make the initial statement plausible.

 

[cesiumfrog]

Just from first principles:

- as a bubble decreases to zero radius, the internal pressure increases infinitly (http://hyperphysics.phy-astr.gsu.edu/hbase/surten2.html#c2").

- the shrinking of the bubble involves the condensation of gas into the surrounding liquid, which is a heating process (opposite of evaporation).

From this I'm naively (neglecting the atomic scale) tempted to conclude that the bubble remains at a "boiling temperature" that with pressure goes also to infinity as the bubble collapses.