Environmental Engineering Reference
In-Depth Information
Also,
L
u
1
,
∂
∂ Ω
=
∂ Ω
=
∂
∂ Ω
L
∂
∂
L
W
ϕ
,
∂
u
1
∂
W
ϕ
∂
∂
∂
W
ϕ
∂
W
ϕ
∂
t
,
=
0
,
n
n
t
∂
t
n
)=
∂
∂
u
1
(
M
,
0
t
W
ϕ
(
M
,
0
)=
ϕ
(
M
)
,
2
∂
∂
)=
∂
a
2
t
u
1
(
M
,
0
t
2
W
ϕ
(
M
,
0
)=
Δ
W
ϕ
(
M
,
0
)=
0
.
∂
Hence,
u
1
=
∂
∂
also satisfies the boundary and initial conditions of
(2.1), so that it is indeed the solution of (2.1).
t
W
ϕ
(
M
,
t
)
2. As
W
f
τ
(
M
,
t
−
τ
)
satisfies
⎧
⎨
2
W
f
τ
∂
∂
a
2
=
W
f
τ
,
Ω
×
(
,
+
∞
)
,
Δ
0
t
2
L
W
f
τ
,
∂
∂ Ω
=
W
f
τ
∂
,
0
n
⎩
t
=
τ
=
W
f
τ
t
=
τ
=
∂
∂
0
,
t
W
f
τ
f
(
M
,
τ
)
,
then
∂
∂
t
t
2
u
3
∂
∂
=
∂
∂
a
2
a
2
t
2
−
Δ
u
3
W
f
τ
(
M
,
t
−
τ
)
d
τ
−
Δ
W
f
τ
(
M
,
t
−
τ
)
d
τ
t
t
0
0
t
W
f
τ
τ
=
t
a
2
t
=
∂
∂
∂
W
f
τ
∂
τ
+
−
W
f
τ
(
,
−
τ
)
d
0
Δ
M
t
d
τ
t
t
0
τ
=
t
−
t
a
2
t
2
W
f
τ
∂
∂
τ
+
∂
W
f
τ
∂
=
d
0
Δ
W
f
τ
(
M
,
t
−
τ
)
d
τ
t
2
t
0
∂
d
t
2
W
f
τ
∂
a
2
=
−
Δ
W
f
τ
τ
+
f
(
M
,
t
)=
f
(
M
,
t
)
.
t
2
0
Therefore,
u
3
satisfies the equation of (2.3).
Also,
L
u
3
,
∂
∂ Ω
=
∂ Ω
L
t
0
t
u
3
∂
∂
∂
W
f
τ
(
M
,
t
−
τ
)
d
τ
,
W
f
τ
(
M
,
t
−
τ
)
d
τ
n
n
0
L
W
f
τ
,
∂
∂ Ω
t
W
f
τ
∂
=
d
τ
=
0
,
n
0
t
=
0
=
W
f
τ
τ
=
t
t
=
0
=
t
∂
u
3
∂
∂
W
f
τ
∂
u
3
|
t
=
0
=
0
,
d
τ
+
0
.
t
t
0
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