【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于验证，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。更多还原

【Abstract】 A 2,3-aimensions hydrodnaxnic numerical model on extended x-coordinate was used tocalculate the tidal current before and after trenching in Hangzhou Bay. A piecewise reversibletransformation is used in the x direchon to map the variable grid into a uniform grid used in thecomputation. The transfomation has the form x = φ(x′) = bx′+ abx′3, where x′ and x are uniformand variable grid respectively, a and b are 1 / 90 and 38.3 for the computational regions, so thatthete are 4 grid points across the channel sechon (width 160km). In order to reduce thecomputahonal hme and have good stability. Two dimension calculation altemating with 3 dimensioncalculation method is empldyed, the former being the alternating direction implicit (ADI)finite-difference method, the later being 3 dimension is the explicit method.The velocity and direchon of tidal current before and after benchjng ddring the spring and neaptide are obtained by numerical modeling. The maximum and venical average venical velocity are169.5 and 106.0cm / s (before benching) 143.5cm/s and 92cm/s (after deepening) during the springtide, the venical average velocity after trenching decreases about 13%, the above correspondingvelocities are 136.5cm / s and 78.5cm / s (before trenching), 113.5cm / s and 66.5cm/s (after trenching)respechocly ddring the neap tide, the vertical average velocity in the deepened channel aftertrenching decreases about 15%. on the venical direction, and the surfase velocity increase about 2%and the bottom velocity decreases about 33-39% due to treanhing. During neap tide, the reducingof bottom velocity is largest.更多还原