河流水体中石油类污染物迁移的数值模拟

Numerical Simulation of Oil Pollutants Transport in River Water

建立了一个平面二维数学模型,以浐河下游河段为例,模拟在点源污染情况下石油类污染物在河水中的迁移,分析其流场与质量浓度场分布规律。采用交替方向隐式技术(ADI)和双扫描法(Double Sweep)求解质量守恒方程和动量方程,采用以QUICKEST格式为基础的三阶有限差分显示格式求解对流扩散方程。结果表明:数值模拟很好地反映了石油类污染物在河水中的迁移扩散情况。该河段流速分布较均匀,只有个别河道狭窄处流速较大;发生点源污染时,大概140min可以形成1km长的污染带,石油类污染严重区域超标18倍以上,下游大多数区域污染超标在2.5-3倍之间,在河水流速增大时,污染范围将更大。

Taking the downstream of Chan River as an example, a two-dimensional horizontal numerical model was established to simulate the transport of oil pollutants when point-source pollution happened in the river. Furthermore,the distributions of flow field and concentration field were analyzed. The mass-conservation equation and the momentum equation were solved by the alternating direction implicit technology and the double sweep method. On the other hand, the convection-diffusion equation was solved by the three order finite difference display format, based on the QUICKEST format. The numerical simulation exactly reflected the diffusion of oil pollutants in the river. The results of simulation showed that the distribution of velocity was basically homogeneous and only individual narrow channels had larger velocity. When pollution happened, 1 km long pollution zone was formed after 140 min. The mass concentration of oil pollutants exceeded the standard 18 times in the most serious area and 2.5 to 3 times in most regions of downstream. With the increase of water velocity, the range of pollution was larger.