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Re: Bernoulli's equation



----- Original Message -----
From: "John Mallinckrodt" <ajmallinckro@CSUPOMONA.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Thursday, January 10, 2002 3:49 PM
Subject: Re: Bernoulli's equation


I don't think one ought to associate the concept of "back
pressure" with Bernoulli's equation since it requires
distinguishing between "upstream" and "downstream", something
Bernoulli's equation manifestly does not do.

Huh? Doesn't Bernoulli's equation deal with laminar fluid flow? There is a
v there, a flow velocity. I don't understand your objection.

Consider the following question:

An ideal fluid flows through the pipe shown below. Where is the
pressure highest and why?
--------
-------- /
\ /
-------------

-------------
/ \
-------- \
--------

If I read correctly, we have a pipe narrowing followed by a pipe
enlarging. At each junction there is a pressure gradient - a pressure
drop at the first junction (where the fluid speeds up), and a pressure
rise at the second junction (where the fluid slows down). I assume a left
to right flow direction in your diagram.
What's the problem?

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor