arman
Guest
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 Posted: Wed Jul 18, 2007 6:37 pm Post subject: sudden expansion in an open shallow water |
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Hi all,
I was wondering if there is such pressure-loss (carnot>s mixing loss)
due to sudden expansion (just like in internal flow; pipe flow) of an
obstacle in open shallow water.
What I mean is, imagine a (rectangular) barge in shallow water subject
to incoming uniform current. In shallow water, there will be a gap
between the base of the barge and the bottom. Part of the current will
flow underneath the barge (off course (large) part of the current will
just flow along the side of the barge). Behind the barge, this
underneath current will more or less experience sudden expansion when
it leaves the barge (from the base-bottom gap to the open water behind
the barge).
Now I wonder if I can use carnot mixing loss formula: deltaH =
(1/2g)*(v1-v2)^2, to estimate the pressure loss behind the barge,
provided that I know the velocity under the barge and the velocity
immediately after (v1 and v2).
The problem is off course the fact that only part of the current flows
underneath the barge (so only this part experiences sudden expansion)
which is differ than in pipe flow where all the current experiences
sudden expansion. I gave up looking for references since I found
none.
Sorry for the (very inperfect) english. Hope you understand what I
mean.
-Arman- |
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