复式断面明渠中污染物混合输移的数值模拟(Ⅰ)——复式断面二次流的模拟

Numerical Simulation on Solute Transport in a Unsymmetrical Compound Channel(Ⅰ)——Secondary Current Simulation

采用L-Y雷诺应力模型,对水面和固壁边界条件进行有效的处理,结合混合有限分析法数值模拟了复式断面明渠二次流流动.和实测资料的对比验证了数值计算和边界处理技术的合理可靠性,并进一步分析复式断面明渠二次流运动的流动结构和特性.发现二次流主要产生在固壁拐角和近岸区域,其中最突出的位置是滩槽结合部,存在明显倾斜指向主槽自由水面的二次流;主流速度等值线被二次流强烈影响凸向二次流指向.

The Launder ＆ Ying algebraic Reynolds stress turbulent model with hybrid finite analytical method is applied to simulate the secondary current in the compound channel. The wall function is adopted such that a resultant stream-wise velocity, U, is expressed by a local friction velocity at a first grid point to the wall of the computation domain. The expression for the dissipation rate given by Rodi at a first grid point of the surface is adopted. The agreement with the experimental data shows that the model and calculate method are available. The result shows the secondary currents are generated near the comers and sidewalls of channel. The isovels of primary mean velocity bulge along the secondary velocities. There are strong, inclined secondary currents in the junction region between the main channel and the floodplain in compound open channel.