Biomedical Engineering Reference
In-Depth Information
(a)
(b)
FIGURE 10.11
Solute release at different Reynolds number
Re
= 125 (a) and
Re
= 1250 (b).
FIGURE 10.12
A marine snow particle of diameter 4 mm. (Courtesy of R. Lampitt.)
This is the reason for the increased interest of the marine scientists in
understanding the sinking and exchange mechanisms generated by the aggre-
gates. Owing to the fact that
in-situ
and laboratory-experiments on living
aggregates are not an easy task, attempts have been made to simulate their
sinking procedure with mathematical techniques.
Until recently, the only model available in the literature was that of
Kiørboe et al. (2001), in which aggregates were considered as a solid sphere.
However, as mentioned earlier, transmission electron microscopy images have
shown that aggregates have a porous structure (Leppard et al. 2004). Hence,
there can be two flow scenarios (Figure 10.13). In the solid case, flow can only
bypass the aggregates, whereas, in the porous case, a partial throughflow also
exists.
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