Environmental Engineering Reference
In-Depth Information
inflowing fluid is the only parameter required. All other boundary conditions, for
solid and fluid phases, are all of no-flow Neumann type.
The complete code is included in the accompanying software under the name
'slowsorp.m'
Exercise 6.4: Compare concentration profiles for a varying solid to fluid transfer
factor
0? The fluid to solid transfer
factor is given by k f ¼ 0 : 02 1/d. Use the following values for the other parameters:
k f . Which known situation is described by
k s ¼
1m 2 /d, v ¼
T ¼
16 d, L =8m, D ¼
0
:
0.5 m/d,
l ¼ l s ¼
0
1200 kg/m 3
y ¼
0
:
2
; r b ¼
; c in ¼
1 mg/l, c 0 ¼ c 0 s ¼
0
Figure 6.6 shows that for a varying transfer rate the solutions lie between two
marginal states. One is given if the transfer factor
0 the
solution is identical to the situation with linear decay, as all mass which disappears
on the solid surfaces has no way back into the fluid. As the figure shows, this
marginal situation already is approached for values
k f
is very low. For
k s ¼
b
1. The other marginal state
is characterized by an immediate back-reaction. The transfer from solid to fluid is
not a limiting factor any more. For the given parameter values this is obviously true
for
k s
k s >
10 5 1/d.
concentration c f
1
T=0
κ s = 1000
T=8
T=16
0.8
κ s =10 5
κ s =10
κ s =10 4
0.6
κ s = 100
κ s =0
0.4
0.2
0
0
2
4
6
8
space
Fig. 6.6 Results of exercise 6.4; on the graphs for T ¼ 16 d the corresponding value of the
transfer factor k f is depicted
 
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