Numerical simulation study on influences of onshore wind on overtopping characteristics of solitary wave under coastal seawall

doi:10.3969-j.issn.1001-909X.2023.04.004

Abstract

Abstract:

Seawalls play an important role in protecting coastal towns from extreme waves damage. Based on two-dimensional incompressible two-phase flow numerical model, the influences of onshore wind on overtopping characteristics of solitary wave under coastal seawall were systematically studied in this paper. The reliability of the numerical model was verified by comparing the numerical results with experimental data, and the influencing factors such as onshore wind speed, incident wave height, crest freeboards of the coastal seawall, beach slope and seawall slope on the hydrodynamic process of solitary wave overtopping of coastal seawalls were discussed in detail. The research results show that with the increase of onshore wind speed, incident wave height and the decrease of crest freeboards of the coastal seawall, the maximum overtopping volume, maximum runup height and spatial distributions of the maximum water elevation gradually increase. With the increase of beach slope and seawall slope, the maximum overtopping volume increase and decrease, respectively, while the maximum runup height gradually increase. Onshore wind can affect the hydrodynamic characteristics of solitary wave overtopping of coastal seawall, increase the wave steepness and the wave crest propagation speed and cause the wave breaking earlier. Compared with the windless condition, the maximum wave overtopping volume, maximum runup height, maximum hydrodynamic forces and spatial distributions of the maximum water elevation are increased under onshore wind. The results of this study can provide a reference for the design of coastal engineering.

Key words: solitary wave, onshore wind, overtopping volume, numerical simulation, hydrodynamic characteristics

CLC Number:

ZHANG Liangbin, QU Ke, HUANG Jingxuan, WANG Xu, GUO Lei. Numerical simulation study on influences of onshore wind on overtopping characteristics of solitary wave under coastal seawall[J]. Journal of Marine Sciences, 2023, 41(4): 32-45.

Figures/Tables 28

Fig.1 Experimental layout[11]

Fig.2 The temporal evolution of wave height for different wave gauges

Fig.3 Spatial distributions of wave elevation at different times

Fig.4 The temporal evolution of solitary wave overtopping volume

Fig.5 Experimental layout[28]

Fig.6 The temporal evolution of wave height for different wave gauges

Fig.7 Computational layout

Tab.1 Parameter setup of numerical simulation and wave breaking types

工况	$U w *$	H/m	A_C/m	cotα	cotβ	破碎类型	工况	$U w *$	H/m	A_C/m	cotα	cotβ	破碎类型
1	0	0.10	0.117	20	2	卷破波	23	4	0.10	0.067	20	2	卷破波
2	1	0.10	0.117	20	2	卷破波	24	0	0.10	0.117	10	2	激破波
3	2	0.10	0.117	20	2	卷破波	25	4	0.10	0.117	10	2	激破波
4	3	0.10	0.117	20	2	卷破波	26	0	0.10	0.117	15	2	卷破波
5	4	0.10	0.117	20	2	卷破波	27	4	0.10	0.117	15	2	卷破波
6	5	0.10	0.117	20	2	卷破波	28	0	0.10	0.117	20	2	卷破波
7	6	0.10	0.117	20	2	卷破波	29	4	0.10	0.117	20	2	卷破波
8	0	0.05	0.117	20	2	卷破波	30	0	0.10	0.117	25	2	卷破波
9	4	0.05	0.117	20	2	卷破波	31	4	0.10	0.117	25	2	卷破波
10	0	0.10	0.117	20	2	卷破波	32	0	0.10	0.117	30	2	卷破波
11	4	0.10	0.117	20	2	卷破波	33	4	0.10	0.117	30	2	卷破波
12	0	0.15	0.117	20	2	卷破波	34	0	0.10	0.117	20	0	卷破波
13	4	0.15	0.117	20	2	卷破波	35	4	0.10	0.117	20	0	卷破波
14	0	0.20	0.117	20	2	卷破波	36	0	0.10	0.117	20	1	卷破波
15	4	0.20	0.117	20	2	卷破波	37	4	0.10	0.117	20	1	卷破波
16	0	0.10	0.217	20	2	卷破波	38	0	0.10	0.117	20	2	卷破波
17	4	0.10	0.217	20	2	卷破波	39	4	0.10	0.117	20	2	卷破波
18	0	0.10	0.167	20	2	卷破波	40	0	0.10	0.117	20	3	卷破波
19	4	0.10	0.167	20	2	卷破波	41	4	0.10	0.117	20	3	卷破波
20	0	0.10	0.117	20	2	卷破波	42	0	0.10	0.117	20	4	卷破波
21	4	0.10	0.117	20	2	卷破波	43	4	0.10	0.117	20	4	卷破波
22	0	0.10	0.067	20	2	卷破波

Tab.1 Parameter setup of numerical simulation and wave breaking types

工况	$U w *$	H/m	A_C/m	cotα	cotβ	破碎类型	工况	$U w *$	H/m	A_C/m	cotα	cotβ	破碎类型
1	0	0.10	0.117	20	2	卷破波	23	4	0.10	0.067	20	2	卷破波
2	1	0.10	0.117	20	2	卷破波	24	0	0.10	0.117	10	2	激破波
3	2	0.10	0.117	20	2	卷破波	25	4	0.10	0.117	10	2	激破波
4	3	0.10	0.117	20	2	卷破波	26	0	0.10	0.117	15	2	卷破波
5	4	0.10	0.117	20	2	卷破波	27	4	0.10	0.117	15	2	卷破波
6	5	0.10	0.117	20	2	卷破波	28	0	0.10	0.117	20	2	卷破波
7	6	0.10	0.117	20	2	卷破波	29	4	0.10	0.117	20	2	卷破波
8	0	0.05	0.117	20	2	卷破波	30	0	0.10	0.117	25	2	卷破波
9	4	0.05	0.117	20	2	卷破波	31	4	0.10	0.117	25	2	卷破波
10	0	0.10	0.117	20	2	卷破波	32	0	0.10	0.117	30	2	卷破波
11	4	0.10	0.117	20	2	卷破波	33	4	0.10	0.117	30	2	卷破波
12	0	0.15	0.117	20	2	卷破波	34	0	0.10	0.117	20	0	卷破波
13	4	0.15	0.117	20	2	卷破波	35	4	0.10	0.117	20	0	卷破波
14	0	0.20	0.117	20	2	卷破波	36	0	0.10	0.117	20	1	卷破波
15	4	0.20	0.117	20	2	卷破波	37	4	0.10	0.117	20	1	卷破波
16	0	0.10	0.217	20	2	卷破波	38	0	0.10	0.117	20	2	卷破波
17	4	0.10	0.217	20	2	卷破波	39	4	0.10	0.117	20	2	卷破波
18	0	0.10	0.167	20	2	卷破波	40	0	0.10	0.117	20	3	卷破波
19	4	0.10	0.167	20	2	卷破波	41	4	0.10	0.117	20	3	卷破波
20	0	0.10	0.117	20	2	卷破波	42	0	0.10	0.117	20	4	卷破波
21	4	0.10	0.117	20	2	卷破波	43	4	0.10	0.117	20	4	卷破波
22	0	0.10	0.067	20	2	卷破波

Fig.8 Velocity contours of water body at different time moments in windy and windless conditions

Fig.9 Comparison of the time series of solitary wave runup height (a) and volume of overtopping water (b) in windy and windless conditions

Fig.10 Hydrodynamic forces exerted at the seawall in windy and windless conditions

Fig.11 Spatial distributions of the maximum water elevation in windy and windless conditions

Fig.12 Comparison of turbulent shear stress between windy (a) and windless (b) conditions

Fig.13 Maximum runup height (a) and maximum overtopping volume (b) of solitary wave under different onshore wind speeds

Fig.14 Comparison of relative wave height for different wave gauges under different onshore wind speeds

Fig.15 Spatial distributions of the maximum water elevation under different onshore wind speeds

Fig.16 Maximum value of runup height (a) and maximum overtopping volume (b) of solitary wave in windy and windless conditions under different incident wave heights

Fig.17 Comparison of relative wave height for different wave gauges in windy and windless conditions under different incident wave heights

Fig.18 Spatial distributions of the maximum water elevation in windy and windless conditions under different incident wave heights

Fig.19 Maximum value of runup height (a) and maximum overtopping volume (b) of solitary wave in windy and windless conditions under different dimensionless crest freeboards

Fig.20 Comparison of relative wave height for different wave gauges in windy and windless conditions under different dimensionless crest freeboards

Fig.21 Spatial distributions of the maximum water elevation in windy and windless conditions under different dimensionless crest freeboards

Fig.22 Maximum value of runup height (a) and maximum overtopping volume (b) of solitary wave in windy and windless conditions under different beach slopes

Fig.23 Comparison of relative wave height for different wave gauges in windy and windless conditions under different beach slopes

Fig.24 Spatial distributions of the maximum water elevation in windy and windless conditions under different beach slopes

Fig.25 Maximum value of runup height (a) and maximum overtopping volume (b) of solitary wave in windy and windless conditions under different seawall slopes

Fig.26 Comparison of relative wave height for different wave gauges in windy and windless conditions under different seawall slopes

Fig.27 Spatial distributions of the maximum water elevation in windy and windless conditions under different seawall slopes

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