Biomedical Engineering Reference
In-Depth Information
U
=
U
0
sin(
v
t
)
L
a
L
L
FIGURE 10.8
Illustration of the geometry and flow condition.
oscillation period, and the diffusion coecient. Finally, the properties of the
sediment, the porosity (
φ
) and permeability (
k
) are also important param-
eters for the interfacial solute exchange. As the results show, each of the
above parameters (
Re,St,Sc,s,φ,k
) are important factors (Liu and Khalili
2010a), however, for the sake of brevity only two cases are shown. These
are streamlines at one-quarter and three-quarter period of time, shown in
Figure 10.9.
Here we only gave two examples. In Figures 10.10 and 10.11, it has been
demonstrated that an increase in the steepness of the ripple and Reynolds
number enhanced the advective transport of the solute at the water-sediment
interface.
10.3.4 Nutrient Release from Sinking Marine Aggregates
Marine aggregates appear in different forms such as discarded feeding struc-
tures, fecal pellets, dead organisms, and other organic debris that sink from
the ocean surface down the water depth to the seabed. Depending on their
density and diameter, aggregates reach terminal velocities ranging from 15 to
30 m/d, and release/adsorb nutrient into/from the ambient seawater. A typi-
cal marine aggregate from the Atlantic with a diameter of 4 mm is shown in
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