OK, I kept the nonsense part of my response on this one to the
implicated parties only.. here is the moresense part:
Nick -
<nonsense about swirlies and Guerin whispering in people's ears in the
bath deleted>
I've stared into a lot of vortices in my time, and I have to say I
find them *very* efficient. I understand that the rotational velocity
of the water (relative to it's actually going *down* the drain) seems
excessive, but my intuition contradicts yours, I suspect that the
water is leaving the drain *faster* than it would be if it were not
aswirl.
I've a rain barrel with a hose outlet near the bottom... the rate of
flow from the hose into my apricot tree does not seem to diminish as
the water level approaches the hose hole and a (noticeable) vortex
forms. There appears to be no vortex until the water level is a few
inches from the hose inlet.
As the head of the water approaches nil, I would expect a significant
drop in flow rate... basic physics would suggest that the resistance
to flow is a function of the (square of) the velocity at the surface
of the hose... viscosity would lead to laminar flow with the center of
the flow being somewhat speedier than at the hose surface. It is
this flow-gradient in a circular context (I believe) that gives rise
to the swirlies... the actual rate of swirling, size of vortex, etc,
is limited by the water viscosity and the pressure (head) methinks.
Stephen is saying "symmetry break! symmetry break!" and I'm nodding in
agreement that without the symmetry break, the water just gurgles on
down.
In the water-bottle swirl example, it is exaggerated because there is
fluid trying to get into the bottom bottle against a counter flow of
air... and the surface tension adds to the obstruction in the
non-swirlie regime.
Maybe our own Peter Lissaman has some insight into this question?
- Steve
Doug,
I knew that if I got no answer from anybody else, I would get one
from you or Steve.
I expected that you would accuse me of being a dissipative structure.
Well, you didn't do THAT exactly.
Actually, ever since those tornados in the spring .. and the one we
had here about 20 miles way ... I have taken anew interest in drain
swirls. The empty space in the middle of the swirl, LOOKS like a
little tornado. Is it one?
Explain your answer. In specific terms. (;-])
N
*From:*[email protected] [mailto:[email protected]]
*On Behalf Of *Douglas Roberts
*Sent:* Tuesday, June 28, 2011 9:03 PM
*To:* The Friday Morning Applied Complexity Coffee Group
*Subject:* Re: [FRIAM] An Open Letter to Steve Guerin
And please, couch your answer in the most general of terms.
:)
-Doug
On Jun 28, 2011 6:59 PM, "Nicholas Thompson"
<[email protected] <mailto:[email protected]>> wrote:
> Dear Steve Guerin,
>
>
>
> I was staring at the water swirling down the drain this evening and I
> thought of you (};-]). It has been a very long time since we have
had any
> kind of conversation on this list about self-organizing systems. I was
> reflecting on the vigor with which the water was rushing AROUND the
basin
> and the slowness with which it seemed to be actually going DOWN the
drain,
> and a little voice said in my ear . I think it was your voice .
that spiral
> in the drain is organized to increase the dissipation of energy.
But then
> my OWN voice said, well then it isn't doing a very good job of it.
>
>
>
> So I wanted to ask you: on your account, do dissipative structures
ALWAYS
> increase the rate of dissipation? Or is it the case that when
structures
> form that obstruct dissipation, these are not dissipative. In which
case,
> what are THESE structures called and when do they form.
>
>
>
> Nick
>
>
>
>
>
> Nicholas S. Thompson
>
> Emeritus Professor of Psychology and Biology
>
> Clark University
>
> http://home.earthlink.net/~nickthompson/naturaldesigns/
<http://home.earthlink.net/%7Enickthompson/naturaldesigns/>
>
> http://www.cusf.org <http://www.cusf.org/>
>
>
>
>
>
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============================================================
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Meets Fridays 9a-11:30 at cafe at St. John's College
lectures, archives, unsubscribe, maps at http://www.friam.org
