Rate of Bubble Expansion

Moonshiners check the quality of their liquor by watching the bubble rise after shaking, but I don't have a clue.

I see a ton of variables to deal with.

Checking Viscosity, I don't think that can be done with air bubbles. maybe a steel ball being dropped. Accuracy would be an issue.

Other than that don't know what is meant by bubbles, but a form of a hydrometer. Like a radiator coolant tester comes to mind.

and when the op talking about flow rates..... the only otherthing comes to mind is a Rotameter that does fluid flow rates

Actually, the bootleggers look at where the bubble rests on the surface line of the liquid

The higher the bubble,the higher the proof.

'Nuff said.

More likely the moonshiners than the bootleggers.

--Ed. Crankshaft

bootleggers are race car drivers...

All bootleggers are race car drivers,but not all race car drivers are bootleggers.

In my neck of the swamp,bootlegger and moonshiner are used interchangeably.

Some used to bootleg liquor,some used to bootleg cigarettes.

The newer generations have moved onto wacky-'backy.

some became politicians... and created a dynasty

Hey! I didn't mention the Kennedy's!

"We hang the petty thieves,and elect the great ones to office"

Quote from an ancient Roman.

Yes. Like farting in a bath........the higher the bubble, the greater the stench. But if you can bear the smell, and have a stopwatch, you could gather some enlightenment on the subject. Could be dangerous though...windows open and no smoking allowed!

Thanks Solar Eagle!

Those are great links! Thanks a lot!

I have nibbled at them cursively,and will make a meal of them later.

Digestion of the data may take a while longer,but it will be assimilated

But there is one piece of information that I did not see,and perhaps I overlooked it in

my skimming of the links.

The Acceleration of the bubble.The "G" force if you were inside the bubble.

Any ideas?

Yes it's covered I think....I saw some graphs dealing with it, or at least some aspects of it....

Kinda looks like a plot of the Hubbell expansion,eh?

Maybe we are on the surface of a bubble,and expansion is a result of external as well as internal forces:

Reduction of outside "pressure"(what ever that is) and internal forces.

Since the energy density of the universe seems to remain constant, there must be a

source of energy from within our bounded universe.

If there were such a thing as the opposite of a black hole, (an UN_Black hole,not a

white hole) it would scatter energy as widely as possible,uniformly,throughout our universe.

It would not be detectible,because it would be uniform in all directions.

All of the matter pulled into the singularity would be converted ultimately to

energy,leaving behind the only remnant of matter,it's gravity,the "bullet hole" so to

speak as it passed through.

I realize I am out of my depth here,and I don't have the math skills to back it up.

Perhaps someone else can either squash this idea or carry it further.

Either way, I will have learned from it.

I also had a cursive (or even cursory!) look and links appear to deal with terminal velocity so no acceleration. As I'm sure you've realized, rising bubble will expand so velocity increase, but if the liquid surface is at atmospheric pressure it would need a fair change in depth to give significant pressure change. As a first approximation, I suppose you could estimate rise velocity at the starting depth and dia, then new dia at higher level due to expansion, hence velocity at that point. Rise/average velocity gives time and acc = velocity change/time. More detailed calc likely to need some calculus but with the inherent uncertainly may not be worth the trouble!

In the experiments in their study, (from your link) they equated the volume of the bubble to a sphere of the same volume.

This is not really a totally honest comparison due to differences in resistance through

the water and vortex shedding that would occur with a sphere.

Consider a bubble,contained in a spherical,flexible membrane,at a great depth and

pressure, that begins with atmospheric pressure,and is then lowered to 100 meters

of water column,without interference with the containment walls,in static water

column.

You know the volume of the sphere at the surface,so calculating the volume at any

diameter would be simple.

Timing would be accomplished in the same manner as the study,unless you were able

to incorporate sonar to detect speed.

Compare it to a hollow sphere of the same volume,like a ping pong ball, released at

the same instant from the same depth.

If there was a method of marking the air molecules in contact with the water, in a

free bubble, I believe the outer surface is constantly shedding towards the

bottom,and the interior molecules are "sliding" past them on the way up.

The outer surface provides a sort of lubricant for the internal molecules.

This molecular movement might even be detectable as heat with the proper equipment.

I know the temperature should be decreasing as the pressure decreases,but I think

there would be a deviation from the ideal calculation.

Minute, I am sure,but it should be there.

I realize this temperature difference would be hard to measure with water being such

a good thermal conductor,and I don't know how it could be done,aside from placing a

sensor within the bubble.

Just thinkin'.

In the perspective of Thermodynamics, its quite complicated.

Static Pressure of Water should be equal to the Pressure inside the bubble.

dP_water = ρgdH; dP_bubble= F/dA_{inside lateral area of sphere} = mRT/dV_sphere --say air is ideal gas. or = const/dV_sphere for polytropic gas.

F_bouyant - W - F_drag = m_air a_bubble

dv_{bubble rising} = (F_bouyant-W-F_drag)dt/m_air

Drag and Bouyant Force is a function of Volume. Mixed it up all from Pressure above and you got your relationships right there and a glass of beer and lots of bubbles in it

are you looking for stokes law?

http://en.wikipedia.org/wiki/Stokes%27_law

By your definition of the problem, no single mathematical statement can accomplish all that you want. You would have better luck at the drive-thru of MacDonald's

Now if you would allow several equations, then you already have what was sought, as presented by Solar Eagle. I will not repeat.

Agreed. For one thing we don't know what bubble size is being considered. With very small bubbles pressure due to surface tension could be significant.

Don't get the MacDonald's joke though

Personally, I hate it when I don't get the joke... so here's a xconsolation joke for you. Hope it's fresh !

At a world brewing convention in the States, the CEOs of various brewing organizations retire to the bar at the end of the day.

Bruce, CEO of Fosters, shouts to the barman:

'InAustralia, we make the best bloody beer in the world, so pour me a Fosters, mate.'

Bob, CEO of Budweiser, calls out next:

'In the States, we brew the king of them all - gimme a Bud.

Hans steps up next:

'In Germany ve invented beer. Give me un Helles, ze REAL King of beers..'

Jan, chief executive of Grolsch, follows by stating that Grolsch is the ultimate beer and asks for one with two fingers of foam on top.

Norman, chairman of SAB, is next:

'Barman, give me a diet Coke with ice and lemon please.'

The other four stare at him in stunned silence, then Bruce asks: 'Aren't you going to have a Castle, Norm?'

Norman replies 'Well, if you guys aren't drinking beer, then neither am I.'

I assume that refers to Castlemaine. You know why Aussies call it XXXX don't you?

Not Castlemaine.. one of SAB's original brews, Castle Lager. I have no clue why Aussies refer to the other as xxxx. Strength, toxicity ?

OK thanks, I assumed Castle was short for Castlemaine.

The reason they call it Castlemaine XXXX is because Aussies can't spell piss

Come to think of it, I don't get it either. I guess you can't get everything you want at Mc D's - or as Mick Jagger would sing: "you can't always get what you want...you can't always get what you want, but if you try sometime....you might just get what you need."

At least the coke at the Golden Arches will have bubbles rising, and you can ask them how fast they rise, how much they expand etc, just to be annoying.