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Wed Nov 7, 2018, 09:12 PM

In case you ever find yourself looking for a monograph on the physics of bubbles, here it is.

Some time ago in this space, I wrote about Lord Rayleigh, at the height of his fame pausing to write a paper about what happens when water boils in a kettle: I just stumbled into a very old paper by "Lord Rayleigh" contemplating water boiling in a pot.

Lately I've been wondering about the physics of bubbles, specifically an unusual case, the physics of a bubble containg metallic gases formed from one or two or more immiscible metals appearing in a viscous liquid phase of another metal. Three metals have extraordinarily long liquid ranges: Gallium, plutonium and neptunium, the boiling points of the latter two having not been subject to direct laboratory measurement but rather inferred by extrapolation of their vapor pressures. (A great deal of plutonium was vaporized in the planetary atmosphere in the late 1940's, all through the 1950's and through much of the early 1960's, with smaller amounts having been so vaporized in rarer cases thereafter: It's still here.)

In the case where we consider doing something practical about reversing currently observed degradation of the climate - not that popular opinion shows even a trace of interest in reality - this situation might be of extreme importance: In liquid plutonium (or liquid neptunium) actively undergoing fission several volatile or potentially volatile metal gases are formed as fission products, notably cesium, rubidium, strontium and barium, as well as several inert gases, xenon, krypton and in proliferation proof plutonium, considerable helium. All of these elements are insoluble in liquid plutonium. Although this same volatility represented the greatest risk associated with the events at Fukushima and Chernobyl - it is also certainly conceivable to technologically exploit this very same process to do certain things, which might well take too long to describe.

Anyway, it took me a long time to locate a general monograph focused specifically on bubble dynamics, but finally I found and obtained one. This is it: Acoustic Cavitation and Bubble Dynamics.

There's two whole sections on Rayleigh's work on bubbles. Here's an excerpt on section 2.1, "Rayleigh–Plesset Equation."

A typical cavitation bubble is filled with vapor and non-condensable gas such as air. The pressure inside a bubble is higher than the liquid pressure at the bubble wall due to surface tension [1, 2]. The surface tension (r) is the surface energy per unit area and is 7.275 10^(−2) (N/m) (= J/m^(2)) for pure water at 20 °C. For a spherical bubble with a radius R, the surface energy is 4σπR^2 because the surface area is 4πR^2...

The next section is on "Rayleigh collapse."

As an aside, my son had the grace to inform me that I've been mispronouncing Rayleigh's name my entire and overly long life by the way, as well as the pronunciation of Auger's name in "Auger electrons" since both scientists' work has relevance to his undergraduate research.

I appreciate that. I'm amazed no one ever corrected me on this score before, either because they assumed I was too stupid to correct or that they had pity on the fact that I was born in Brooklyn.

You may never have any interest in the physics of bubbles; most people don't, and I didn't for much of an overly long life, but in case you do, here's a shortcut to avoid spending as much time as I did to find a comprehensive monograph on the subject of bubbles.

Have a nice day tomorrow.

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Reply In case you ever find yourself looking for a monograph on the physics of bubbles, here it is. (Original post)
NNadir Nov 7 OP
AJT Nov 7 #1
Turbineguy Nov 7 #2
NNadir Nov 7 #3

Response to NNadir (Original post)

Wed Nov 7, 2018, 09:21 PM

1. I was just thinking the other day.....bubbles....I want to know more about the physics of bubbles...

Actually, what little I could understand of this, was quite interesting. So, thanks.

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Response to NNadir (Original post)

Wed Nov 7, 2018, 09:21 PM

2. Bubbles are a big deal in boilers

because they cause carryover of chemicals into the superheaters where they plate out and cause tube failure.

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Response to Turbineguy (Reply #2)

Wed Nov 7, 2018, 10:04 PM

3. Yes, I'm aware of this, which is why I found it so surprising that it was difficult to find...

...a nice comprehensive monograph on the subject.

Many heat transfer texts have discussions of all that Nukiyama stuff, nucleate boiling, film boiling/leidenfrost effect, etc, etc, but my interest was somewhat more esoteric, since the question I was asking myself was how might the behavior of bubbles affect fission reactivity in a liquid actinide solution.

Literature on the conceptually marvelous LAMPRE reactor that operated in the early 1960's at Los Alamos referred to a decrease in reactivity owing to an effect rather like nucleate boiling, gas bubbles (xenon) adhering to the walls of the tantalum capsules they used. They ultimately managed to get around this, but I would think that since tantalum is a conflict metal, an ethical reactor, a sustainable reactor, of this type would avoid the use of tantalum. I think a modern version would need to operate at much higher temperatures than LAMPRE did in any case, which would be a good reason to understand the very basic physics of bubbles.

The interesting thing about this system, is that in a fission system, liquid plutonium would have an evolving composition. If the reactor was used to denature weapons grade plutonium by direct introduction of dismantled bomb cores, the system would also contain gallium besides evolving fission products.

It's a beautiful problem, I think.

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