September 2013
Intermediate to advanced
320 pages
11h 25m
English
Content preview from Finite Element Techniques for Fluid Flow
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240 SHALLOW WATER CIRCULATION PROBLEMS
We
can
transform again
to
calculate
N
nn
and
N
ns
N
n
„
=
0L
nl
N
nl
+
cc
n2
N
n2
On land type boundaries
we
usually have
q
n
= 0
on
S
l
(7.25)
However,
if a
river enters
the
body
of
water
we can
specify
its
mass
input
as
q
n
= q
n
= {q}
river inflow
/ „ .
>
on
part
of 5χ
boundary (7.26)
4s
= 0 J
On
an
ocean boundary
one has to
prescribe
in
principle
the
normal
and
tangential forces
_ onS
2
7.27)
N
= N
iy
ns
l
*
ns
J
but
as the
eddy viscosity terms
in
(7.20)
are
generally neglected,
the
tangential forces
or
velocities cannot
be
prescribed. Hence
our
boundary conditions reduce
to
q
n
= 0 or q
n
=
q
n
on
S
l
plus
_
(7.28)