Environmental Engineering Reference
In-Depth Information
12
Pe=1 / 100
Pe=1 / 400
Pe=1 / 1600
10
8
6
4
2
0
0
20
40
60
80
100
space (250*
ξ
)
Fig. 16.2 Transport solution for instantaneous source in dependence of the P´clet number
Pe
Chap. 5. The dependence of the transport solution for dimensionless time
1on
the P´clet number is visualized in Fig.
16.2
. The figure was obtained using the M-
file
'GaussianPuff.m
' with input data:
t ¼
in three runs with different diffusivities:
It is instructive to view the development of the concentration profile in the space-
time diagram. Such an illustration is given in Fig.
16.3
, which was obtained using
the M-file
'GaussianPuff.m
' with input data:
A more generalized formulation of the normal distribution is valid for substances
that are subject to degradation or decay processes in addition. If
l
refers to the
decay coefficient, one obtains the formula:
!
2
4
tD
lt
M
4
ð
x
vt
Þ
p
p
D
cðx; tÞ¼
exp
(16.7)
pt
