The hydrodynamic performance of regular wave-two vertical plates-topography coupled system, comprised by two vertical penetrating plates mounted over a stepped bottom (submerged breakwater) with different dimensions, were analyzed by the use of the toolbox waves2Foam based on the open source software OpenFOAM. The effects of the gap between the two plates and the dimension of the stepped bottom on the hydrodynamic characteristics, such as reflection and transmission coefficients, viscous dissipation ratio of wave energy, and relative oscillating amplitude of the free surface between the two plates, were examined systematically under the action of different incident waves. In addition, the nonlinear effect of wave on the hydrodynamic parameters was investigated. Results showed that a proper dimension of the stepped bottom, for example that the ratio of topography length to wavelength was approximately equal to 1.0, was beneficial for reducing the reflection and transmission coefficients and obtaining a satisfactory viscous dissipation ratio. The presence of the stepped bottom enhances the oscillating amplitude of the free surface between the two plates and effectively improves the capacity of capturing wave energy. Furthermore, the increase of wave height leads to the reduction of the reflection and transmission coefficients, the enhancement of the viscous dissipation ratio, and the drop of the oscillating amplitude of the free surface between the two plates.
Chen WANG,Zheng-zhi DENG,Da-wei MAO. Hydrodynamic performance of two vertical plates penetrating system mounted over stepped bottom. Journal of ZheJiang University (Engineering Science), 2019, 53(2): 336-346.
Fig.1Schematic diagram of absorbing waves for numerical wave tank
Fig.2Numerical convergence study for grid size and time step
T/s
x=L
x=2L
x=3L
x=4L
x=5L
0.9
0.019 9
0.019 9
0.019 8
0.019 7
0.019 6
1.0
0.019 9
0.019 8
0.019 8
0.019 7
0.019 7
1.1
0.020 0
0.019 8
0.019 8
0.019 9
0.019 9
1.2
0.019 9
0.019 9
0.019 8
0.019 9
0.019 7
Tab.1Wave heights for places with different distances from wave-making boundary under different periods
Fig.3Results of absorbing wave at inlet and outlet
Fig.4Schematic diagram of two vertical plates model and wave surface monitoring locations
Fig.5Comparison between present numerical wave elevation results and analytical, experimental results for two vertical plates model
Fig.6T-type structure model for verification of separation of reflection coefficient
Fig.7Comparison of results for separation of reflection coefficient
Fig.8Schematic diagram of two vertical plates with varied sea-bottom
工况
固定参数
变化参数Ⅰ
变化参数Ⅱ
1
H=0.02 m, T=1.2 s
b/h=0.1,0.2,0.3,0.4,0.5
B/L=0,0.4,0.5,0.6,0.9,1.0,1.1,1.5,2.0
2
b/h=0.1, T=0.9 s
H=0.005,0.010,0.015,0.020,0.025 m
B/L=0,0.4,0.5,0.6,0.9,1.0,1.1,1.5,2.0
Tab.2Parameters for model calculation of two vertical plates system over a stepped bottom
Fig.9Time series of wave surface elevations for gages in interior of two vertical plates
位置属性
测点G
ΔL/m
位置属性
测点G
ΔL/m
1
3.10
6
11.86
双垂板前定水深
2
7.00
双垂板内部
7
11.95
3
8.00
8
12.04
双垂板前变水深
4
11.60
双垂板后方
9
15.00
5
11.80
—
—
—
Tab.3Locations for monitoring wave surface elevation in numerical wave tank
Fig.11Transmission coefficient against relative crest width under different interval ratios of two vertical plates
Fig.12Energy dissipation rate against relative crest width under different interval ratios of two vertical plates
Fig.13Streamline diagram at different intervals without stepped bottom
Fig.14Streamline diagram at different intervals with stepped bottom
Fig.10Reflection coefficient against relative crest width under different interval ratios of two vertical plates
Fig.15Relative wave height between plates against relative crest width
Fig.19Nonlinear effect on energy dissipation rate of two vertical plates system under different incident wave heights
Fig.16Nonlinear effect on high order waves for outside and inside of vertical plates
Fig.17Nonlinear effect on reflection coefficient of two vertical plates system under different incident wave heights
Fig.18Nonlinear effect on transmission coefficient of two vertical plates system under different incident wave heights
Fig.20Nonlinear effect on relative wave height between plates of two vertical plates system under different incident wave heights
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