海水经船闸入侵淡水运河的三维数值模拟

为研究船闸运行过程中盐分的输运规律及其对淡水水域的盐度影响,建立了三维k-ε两相混合流数值模型,模型控制方程组采用有限体积法进行离散,流速与压力耦合采用SIMPLEC算法,时间项采用一阶隐式格式,流项采用二阶迎风格式,计算区域采用六面体网格划分。采用某船闸的海水入侵原型试验成果对数值模型进行了验证,闸室内盐度的模拟值与实测值吻合较好。海水入侵淡水水域模拟结果表明:上游航道盐度分布可分为异重流段、过渡段和扩散段,各段盐分输运速度依次减小;各断面的盐度呈周期性变化,在船闸运行一段时间后逐步趋于动态平衡;一个循环内的盐分入侵量在船闸运行初期较大,随着运行时间的增加逐渐减小,并趋于恒定值。研究结果可为船闸的设计与运行调度提供科学依据。

Three-dimensional Numerical Simulation on Seawater Intrusion into Freshwater Canal Through Ship Lock

In order to study the law of salt transportation in the operation of ship lock and its influence on salinity in freshwater area, we set up a three?dimensional numerical model for k?εtwo?phase mixed flow. In the model, control equation groups are dispersed by finite volume method, velocity?pressure coupling by SIMPLEC algorithm, time term by single?order implicit expression, and convection term by second?order upwind scheme, with computing area divided by hexahedral mesh. This model is verified by comparison with prototype experimental results of sea water intrusion into a ship lock, and simulated data are well in agreement with measured data of salinity in lock chamber. The simulation results about the process of seawater intrusion into freshwater zone show that 1) distribution of salini?ty in upstream waterway can be divided to 3 sections:density current section, transition section and diffusion sec?tion, whose salt transporting speed reduces in order;2) salinity periodically changes at each section and it gradual?ly tends to be at a dynamic balance after ship lock operates for a period;3) as for a given cycle, saline intrusion quantity is big at early stage of ship lock operation, then, it gradually reduces and tends to be stable. The research results offer scientific reference for the design and operation of ship lock.