Re: What is the maximum size for a drop of water?
- From: bobg@xxxxxxxxx (Robert Grumbine)
- Date: Thu, 31 Aug 2006 17:55:53 -0000
In article <1157042711.022172.109290@xxxxxxxxxxxxxxxxxxxxxxxxxxx>,
rev.goetz <jimgoetz316@xxxxxxxxx> wrote:
In some cases, combining 2 drops of water make a bigger drop of water.
But what is the maximum size for a drop of water? Seriously, I assume
that there is some physical constraint for the size of a drop of water.
Some eons (net-time) ago, I worked out some examples for martian
raindrops. I think it was prompted by the velikovskian incursion.
(call it 1996-ish for your googling)
For a droplet freely falling through air the balance is between
the stagnation pressure of the air as the drop falls through it
and the surface tension strength. The droplet can be assumed to
be at terminal velocity.
As air density increases, terminal velocity decreases. As
gravity increases, terminal velocity increases. As radius increases,
terminal velocity increases. As radius increases, surface tension
strength (as opposed to the molecular value) decreases (as 1/radius).
Stagnation pressure is proportional to the square of the velocity.
So you'll have a limit. Holding other things fixed, increasingly
larger drops are subject to greater forces, and have less strength
to resist disruption. (see that old note for a worked out example.)
--
Robert Grumbine http://www.radix.net/~bobg/ Science faqs and amateur activities notes and links.
Sagredo (Galileo Galilei) "You present these recondite matters with too much
evidence and ease; this great facility makes them less appreciated than they
would be had they been presented in a more abstruse manner." Two New Sciences
.
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