| 摘要: |
| 采用x方向伸展坐标下的二、三维方程，建立了开辟或增深深水航道前后的潮流场数值模式。该模式在航道横向上网格变距，以保证航道横向上有一定量的网格覆盖。在计算中采用二、三维交替进行，既节省大量计算时间，又保证了计算的稳定性。模式应用在杭州湾深水航道试挖研究中，用5个测流站大、中、小潮各层的观测资料给予验证，流速相对平均误差为6%-10%，流向平均偏差大都在10°之间。计算表明在杭州湾航道增深4m后，垂直平均流速将减小15cm/s左右（约减小16%）。但在垂向上变化是不同的，底层减小较大，而表层还略有增大；流向挖前挖后除槽内底层外，几乎没有变化。 |
| 关键词: 数值模拟 潮流 深水航道 伸展坐标 分段双向转换 杭州湾 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金资助项目，49276261号 |
附件 |
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| NUMERICAL STUDY ON THE EFFECT OF DEEPENING CHANNEL ON TIDAL CURRENTS IN THE HANGZHOU BAY |
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LI Shen-duo1,2, WANG Xing-heng1,2, MEI Xiang-qi3,4,2
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1.State Key Laboratory of Estuarine and Coastal Research,East China Normal University, Shanghai;200062;3.Compute Central, East China Normel University, Shanghai,200062;4.Institute of Estuarine and Coastal Research,East China Normal University, Shanghai
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| Abstract: |
| A 2,3-dimensions hydrodynamic numerical model on extended x-coordinate was used to calculate the tidal current before and after trenching in Hangzhou Bay. A piecewise reversible transformation is used in the x direction to map the variable grid into a uniform grid used in the computation. The transformation has the form x=phi(x')=bx'+abx'3, where x'and x are uniform and variable grid respectively, a and b are 1/90 and 38.3 for the computational regions, so that there are 4 grid points across the channel section (width 160 km). In order to reduce the computational time and have good stability. Two dimension calculation alternating with 3 dimension calculation method is employed, the former being the alternating direction implicit (ADI) finite-difference method, the latter being 3 dimension is the explicit method.
The velocity and direction of tidal current before and after trenching during the spring and neap tide are obtained by numerical modeling. The maximum and vertical average vertical velocity are 169.5 and l06.0 cm/s (before trenching) 143.5 cm/s and 92 cm/s (after deepening) during the spring tide, the vertical average velocity after trenching decreases about 13%, the above corresponding velocities are 136.5 cm/s and 78.5 cm/s (before trenching), 113.5 cm/s and 66.5 cm/s (after trenching) respectively during the neap tide, the vertical average velocity in the deepened channel after trenching decreases about 15%. On the vertical direction, and the surface velocity increase about 2% and the bottom velocity decreases about 33%-39% due to trenching. During neap tide, the reducing of bottom velocity is largest. |
| Key words: Numerical modeling, Tidal current, Deepen channel, Extended x-coordinate, Piecewise reversible transformation, Hangzhou Bay |
