﻿ 水东湾地貌形态演变数值模拟
 海洋科学  2018, Vol. 42 Issue (11): 64-72 PDF
http://dx.doi.org/10.11759/hykx20180205001

文章信息

LI Qing-yuan, ZOU Zhi-li, CHANG Cheng-shu. 2018.

Numerical simulation of the evolution of the morphological features of Shuidong Bay

Marina Sciences, 42(11): 64-72.
http://dx.doi.org/10.11759/hykx20180205001

文章历史

Numerical simulation of the evolution of the morphological features of Shuidong Bay
LI Qing-yuan, ZOU Zhi-li, CHANG Cheng-shu
State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China
Abstract: To analyze the formation mechanism of an island in a lagoon-type bay, the coupling model of horizontal 2-D tidal current, sediment transport, and terrain evolution is adopted to reproduce the morphological features of Shuidong Bay and the focus is on the formation and evolution of Dazhou Island in Shuidong Bay. The calculation results are consistent with the actual topography. Two models of sediment transport, i.e., total load and bed load sand transport models, are considered. The simulation shows that Dazhou Island in Shuidong Bay is formed by the continuous deposition of silts in the lagoon under the influence of rising tide and is a geomorphic form of flood tide delta. The total load sediment transport model is more suitable for simulating the terrain evolution process than the bed load sediment transport model. This study explores the formation mechanism and evolution process of the general bay morphology through numerical simulation.
Key words: tidal channel    terrain evolution    tidal    numerical simulation

1 水东湾地貌特征

 图 1 水东湾地貌形态 Fig. 1 Morphological features of Shuidong Bay

2 计算模型及验证 2.1 计算模型

 $\frac{{\partial \eta }}{{\partial t}} + \frac{{\partial (Hu)}}{{\partial x}} + \frac{{\partial (Hv)}}{{\partial y}} = 0$ . (1)

x方向动量方程:

 $\frac{{\partial u}}{{\partial t}} + u\frac{{\partial u}}{{\partial x}} + v\frac{{\partial u}}{{\partial y}} = fv - {\rm{g}}\frac{{\partial \eta }}{{\partial x}} - {\rm{g}}\frac{{u\sqrt {{u^2} + {v^2}} }}{{C_z^2H}}$ , (2)

y方向动量方程:

 $\frac{{\partial v}}{{\partial t}} + u\frac{{\partial v}}{{\partial x}} + v\frac{{\partial v}}{{\partial y}} = - fu - {\rm{g}}\frac{{\partial \eta }}{{\partial y}} - {\rm{g}}\frac{{v\sqrt {{u^2} + {v^2}} }}{{C_z^2H}}$ , (3)

 $(1 - {{\rm{n}}_p})\frac{{\partial {z_b}}}{{\partial t}} + \frac{{\partial {q_x}}}{{\partial x}} + \frac{{\partial {q_y}}}{{\partial y}} = 0$ (4)

 $\boldsymbol{q}={\rm{m}}|\boldsymbol{u}|^{2} \boldsymbol{u}$ (5)

 $\boldsymbol{q}_{s}=\frac{0.05 \alpha|\boldsymbol{u}|^{4} \boldsymbol{u}}{\mathit{\boldsymbol{g}}^{0.5} C_{z}^{3} \Delta^{2} \mathit{\boldsymbol{d}}_{50}}$ (6)

2.2 边界条件

 图 2 水东湾计算区域及水深图 Fig. 2 Computational domain and chart depth of Shuidong Bay

 $\eta = {\rm{A}}\sin \omega t$ (7)

2.3 模型验证

 图 3 潮位、流速验证图 Fig. 3 Comparison of tide level and velocity

 图 4 水东湾潮流流场模拟结果 Fig. 4 Numerical results of the velocity field 注: a.涨急流场; b.落急流场 Note: a. moment for maximum flooding current; b. moment for maximum ebb current
3 水东湾计算模拟结果

 图 5 从初始到20 a水东湾地形模拟结果(全沙输沙模式) Fig. 5 Evolution of the topography of Shuidong Bay for 5, 15, and 20 years
3.1 全沙输沙模式的结果

 长度/km 宽度/km 面积/km2 5年平均增长率/(km2/a) 全沙输沙模式 推移质输沙模式 全沙输沙模式 推移质输沙模式 全沙输沙模式 推移质输沙模式 全沙输沙模式 推移质输沙模式 5 a 0.95 0.28 0.27 0.15 0.1 0.06 10 a 1.92 0.51 0.37 0.42 0.43 0.19 0.066 0.026 15 a 1.41 0.62 0.42 0.55 0.56 0.24 0.026 0.01 20 a 1.73 0.83 0.6 0.61 0.83 0.45 0.054 0.042 25 a 1.73 1.05 0.61 0.72 0.85 0.76 0.004 0.062

 图 6 水东湾实际地形平面图 Fig. 6 Present topography of Shuidong Bay
3.2 推移质输沙模式的结果

 图 7 从初始到25 a水东湾地形模拟结果(推移质输沙模式) Fig. 7 Evolution of the topography of Shuidong Bay for 5, 15, and 25 years

 图 8 湾中岛不同年份等深线图 Fig. 8 Contour map of Wanzhong Island for different years 注: a.全沙输沙模式; b.推移质输沙模式 Note: a. total load sand transport model; b. bed load sand transport model
4 讨论

4.1 涨潮三角洲模拟分析

4.2 落潮三角洲模拟分析

5 结论

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