The Investigation of the Hydrodynamics of an Artificial Reef - Aquaculture and the Environment: A Shared Destiny - page 90

upwelling flow velocity does not always increase with the reef height, and the maximum
value is obtained at 8.0. The maximum average upwelling flow velocity is nearly a quarter
of the inlet flow velocity.
4.2.3 The effect of reef height on the scale of the upwelling field
To find the best size of the artificial reef, a new conception unit artificial reef effect is
introduced. It is weighed by length and area, and the unit artificial reef effect relative to the
height and area of the upwelling field is represented by H upA = H up / h and S upA = S up / S .
As shown in Fig. 10, the result of regression found that the height of the upwelling field and
the reef height have a positive linear relationship. The best fit equation between H up (axis y)
and h (axis x) is y=1.76x-0.62, which is obtained by the linear regression analysis method,
and the R² (correlation coefficient) is 0.9997. According to Fig. 10, when the reef height is 7.5
cm and 10.0 cm, H upA (the ration of H up to h ) is large. Thus, the preferable unit artificial reef
effect relative to H up was acquired at the reef height of 7.5 cm and 10.0 cm.
Fig. 10. H up and H upA with different heights of artificial reefs
The area of the upwelling field and the reef height were fitted by the nonlinear regression
analysis method, i.e., a second-order polynomial regression. The relationship between S up
(y) and h (x) can be expressed by the equation y=0.86x 2 -2.51x+3.87 and R² = 0.9979. Fig. 11
shows that the curves of S upA are the same as those for H upA , and both of them acquire a
large value at the reef heights of 7.5 cm and 10.0 cm. Thus, a preferable unit artificial reef
effect relative to S up is acquired at the reef heights of 7.5 cm and 10.0 cm.
Fig. 11. S up and S upA with different heights of artificial reefs