Biomedical Engineering Reference
In-Depth Information
30
30
25
25
AB
20
2.00E-02
20
1.83E-02
1.67E-02
1.50E-02
15
1.33E-02
15
1.17E-02
1.00E-02
8.33E-03
6.67E-03
5.00E-03
10
10
5
5
0
0
0
0
5
10
15
5
10
15
X
X
FIGURE 7.5
Distribution of the biomass produced by SPH Model 1 for two different val-
ues of
τ
cr
. Gray particles denote soil grains, black particles represent fluid
particle with nonzero biomass concentration, and the quasicontinuous gray
scale indicates the concentration product,
AB
, in the fluid particles with zero
biomass concentration (Tartakovsky et al. 2009). (Tartakovsky, A.M., Scheibe,
T.D., and Meakin, P.,
J. Por. Med.
, 12, 5, 2009. Copyright 2009 Bagell House.
Modified from Bagell House.)
near the fracture entrance preventing biomass growth further along the frac-
ture walls. The biomass grew in the form of bridges between the soil grains
oriented in the direction of the flow. The mixing zone between solutes
A
and
B
did not extend far enough into the porous matrix to facilitate substantial
growth of the biomass in the porous matrix. For the larger critical stress,
τ
cr
,
the biomass extended further toward the middle of the fracture but still grew
only near the fracture entrance.
Figure 7.6 shows the distribution of biomass resulting from Model 2. It can
be seen that, as in Model 1 with smaller
τ
cr
, the biomass grew between soil
grains where the fluid stresses were the smallest. However, owing to the attach-
ment/detachment mechanism included in the Model 2 the biomass spreads
along the whole length of the fracture, completely sealing the fracture walls.
Comparison of Figures 7.5 and 7.6 shows similar distributions of the concen-
trations of
A
and
B
but very different distributions of the biomass, indicating
the
dominant
role of the attachment/detachment mechanism in the biomass
growth and spreading. The difference between the results of Model 1 and 2
demonstrates the importance of realistic treatment of biomass that is mostly
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