Fluid dynamics of a cocktail shaker

[phinds]

My son today asked me for an analysis of a situation, which was described to him as being purely anecdotal but apparently a fairly widespread belief among bartenders, so possibly correct.

The description is that if you take the two metal halves of a cocktail shaker, with a normal compliment of liquid stuff and then add either:

(1) a bunch or normal sized ice cubes
(2) a single much larger ice cube

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You get different degrees of "frothiness" in the resulting drink when shaken. My expectation was that the multiple cubes would lead to more frothiness but he said the consensus is that the single cube leads to more frothiness.

Now this is a very UN-controlled experiment. For one thing, he thinks that generally with a single cube, more shaking is done (longer time) in order to achieve the same degree of temperature/dilution but that's not definite.

My own explanations were that if indeed this is a valid description of results, there are two possible reasons:
(1) they do in fact shake for longer and it's just that longer shaking leads to more frothiness
(2) the smaller cubes bang together and create more localized shock waves that collapse some of the tiny bubbles and cause some of the gas to be reabsorbed than would be the case with far fewer shock waves of just one big cube hitting the ends of the shaker.

So ... anyone have any more enlightened take on what might be going on (again, assuming that the outcome is in fact correctly described) ?

Thanks,

Paul

 

[Grinkle]

Speculation -

Maybe its about the pour. Perhaps multiple cubes tend to filter out bubbles as the drink is poured into the glass, and a single large cube does not do that.

 

[fresh_42]

I wonder whether there is a Mythbusters episode with this question ...

 

[phinds]

One time bump.

Any other ideas?

 

[fresh_42]

My expectation was that the multiple cubes would lead to more frothiness

Sorry, I agree.

 

[Bystander]

Is there a "strainer" on the shaker?

 

[phinds]

Is there a "strainer" on the shaker?

Nope, just two metal cylinders with one end open and one end closed on each, with a flared angle. The smaller open end fits inside the larger open end while shaking.

 

[Bystander]

This is a "mixture" and like all mixtures exhibits "surfactant" behaviors (the frothiness, or suspension of air among others); but, I'm at a loss to explain "single cube frothier" as anything other than

Maybe its about the pour. Perhaps multiple cubes tend to filter out bubbles as the drink is poured into the glass, and a single large cube does not do that.

 

[phinds]

Speculation -

Maybe its about the pour. Perhaps multiple cubes tend to filter out bubbles as the drink is poured into the glass, and a single large cube does not do that.

But the bubbles are CREATED by the shaking. They don't exist prior to the shaking.

 

[Bystander]

bubbles are CREATED by the shaking.

... but, after being suspended, the single cube does less to "break the suspension."

 

[phinds]

... but, after being suspended, the single cube does less to "break the suspension."

That's my explanation #2

 

[ChemAir]

I'd wonder about final temperature and amount of dilution by the ice. Both will affect viscosity, and probably surface tension. If shaken for the same time, the higher surface area may cool the blend much more quickly than a single large piece.

For a real test, it would seem you might want the final temperature, concentration, and excess ice mass to be the same in both cases to eliminate these as possibilities.

 

[phinds]

For a real test, it would seem you might want the final temperature, concentration, and excess ice mass to be the same in both cases to eliminate these as possibilities.

Yes. As I said, this was a very UNcontrolled experiment.