Agriculture Reference
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0.5
Distance-dependent
Time-dependent
L
= 50 cm
0.4
0.3
0.2
0.1
0.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Pore Volume
(a)
1.0
Distance-dependent
Time-dependent
L
= 100 cm
0.8
0.6
0.4
0.2
0.0
0
1
2
3
4
5
6
Pore Volume
(b)
FIGURE 4.1
Comparison of simulated breakthrough curves based on time-dependent (Equation 4.8) and
distance-dependent (Equaton 4.16) dispersivity for 50 cm (top) and 100 cm (bottom) columns.
edge, however. BTCs for the distance-dependent cases showed higher peak
concentrations than those for the time-dependent cases. In general, time-
dependent α resulted in enhanced tailing compared with distance-dependent
counterparts.
Snapshots for solute distributions at different times for the 100-cm col-
umn with linear time-dependent or distance-dependent α are shown in
Figure 4.2. Because the dispersion coefficient vanishes at the inlet (
x
=
0) for
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