Re: Bernoulli Principle, 2nd try

[pvalev <pvalev@BAS.BG>]

--- Tucker Hiatt <thiatt@USFCA.EDU> wrote:

> Finally, to throw gasoline on the fire, let me pose a gedanken
> experiment that seems to identify another (related?) problem with
the
> BP as conventionally, conceptually understood.
>
> Suppose a very long train moves through a very long, straight
tunnel.
> We conventionally invoke the BP to explain why smoke from a cigar in
> the train's "smoking car" flows out the window into the air of the
> tunnel.  We say the air pressure is lower outside the train because,
> relative to the train, the tunnel's air is flowing past.  But what
> about the smoke from a cigar at rest within the tunnel?  Shouldn't
> that smoke flow into the window of the passing train?  After all,
the
> air pressure is lower inside the train because, relative to the
> tunnel, the train's air is flowing past!


I think the answer to this conundrum may be the solution to
Bernoulli's problem as well. By friction, the lateral walls
of the train push air molecules in the direction of
movement and so leave an area depleted of air molecules,
with lower air pressure, behind them.
Something similar must happen when there is a flow parallel to
the submarine wall.

Pentcho