Environmental Engineering Reference
In-Depth Information
Fig. 21. Distribution of the horizontal flow velocities of two vertical artificial reefs along the
line of Y=0 at the horizontal cross-section of Z=1/2
h
(
h
=7.5 cm)
6. Conclusions
Some main conclusions can be drawn as follows:
1.
The flow field within and around a single hollow cube artificial reef was investigated by
physical experiments and numerical simulations. The upwelling and back vortex flow
fields that arose from artificial reefs were analyzed by using qualitative and
quantitative analysis methods. According to the comparisons, there is a good
agreement between the numerical and experimental results.
2.
Based on the experimental verification, a detailed numerical study was conducted to
investigate the effect of reef height on the structure of the flow field. The height and
area of upwelling current region increased linearly and nonlinearly with increasing reef
height, respectively. When the value of r (the reef height to water-depth) was 0.2, the
normalized maximum and average upwelling flow velocities reached their maximum
values. An exponential growth relationship existed between the length of the back
vortex flow and the reef height. The flow field on either side of artificial reef was also
discussed. A preferable unit artificial reef effect was achieved when the ratio of the reef
height to water-depth was 0.2.
3.
In the meantime, the influence of the arrangement (parallel and vertical) and spacing on
the flow field of the two artificial reefs were discussed using the results of the numerical
method. In the parallel combination, the scale of the upwelling field reached the
maximum value, and a larger area of slow velocity flow field was obtained. The
interaction between the two reefs was slight after the spacing became larger than 2.0
h.
In
the vertical combination, the latter artificial reef had a weaker effect on the
distribution of flow velocities within and in the front of the first artificial reef. When the
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