Re: [Phys-l] Entrainment of oil in Hurricane?

["LaMontagne, Bob" <RLAMONT@providence.edu>]

Entrain doesn't really equate to "suck". Turbulent entrainment is a mechanical mixing along the boundaries of a flow that continuously decays to smaller scales.

Also, a fast stream of air, say from a hair dryer, does not have a pressure at its core that is any different than the surrounding static air - hence no "suction" is involved. This can be easily demonstated with a water-filled U shaped tube attached to a hose in the moving air and a hose in the static air. The pressure difference is zero if the tube mouth is properly aligned so it is not reading "ram" pressure or deflecting the air stream.

A spray of water in a shower "entrains" air by physically pushing it along the direction of the spray - some use this to explain why shower curtains often move inward when the spray is started.

Bob at PC

________________________________________
From: phys-l-bounces@carnot.physics.buffalo.edu [phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of Bernard Cleyet [bernardcleyet@redshift.com]
Sent: Thursday, June 24, 2010 6:36 PM
To: Forum for Physics Educators
Cc: Bryan Mumford; T.K.Wang & Mary Brooks; Nancy Seese
Subject: Re: [Phys-l] Entrainment of oil in Hurricane?

I don't like that use of entrain**, even tho it's commonly used as a substitute for suck***.  For a time I objected to the use of suck, even to the extent of telling people i didn't use a vacuum cleaner, but a suction cleaner.

This reminds me of diffusion pumps.  Are they Bernoulli or suction pumps?



**  the oil is not already in the atmosphere so entrain is not a "correct" use for that word.  One doesn't say, the roof was entrained into the tornado, but blown up into.  (by the overpressure of the house under the roof.)

http://mw4.m-w.com/dictionary/entrain

*** Now completely accepted as describing the method of making noise at the end of milkshake consumption.

http://www.thefreedictionary.com/suck


bc giving up being a strict prescriptivist

p.s. on second thought I'm wrong.  the wind whips up spume which is carried along w/ the wind and when it slows drops it's load just as water does to silt at the alluvial or bend in the river.


On 2010, Jun 24, , at 14:52, Peter Schoch wrote:

> I object to his terminology of 'sucked into', I prefer entrained.  However, the possibility is intriguing.  With lower pressure, shouldn't the top layers of the gulf (and thus the oil) be entrained into the hurricane and thus be 'rained out' over the inland regions causing an even greater ecological problem?!

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