Numerical Study of Submerged Vertical Plane Jets Under Progressive Water Surface Waves
Numerical Study of Submerged Vertical Plane Jets Under Progressive Water Surface Waves
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发表时间：
2005
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通讯作者：
Dai Huichao
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作者：
Dai Huichao
当废水通过排水系统排放到沿海地区时，它将始终受到波浪的作用。研究和量化排放与周围水的混合情况，以便对这种排放条件进行准确的环境影响评价是很重要的。本工作旨在研究平面射流以规则波排入水环境的现象。建立了基于全Navier-Stokes方程（NSE）在σ-坐标系下的三维数值模型来研究这一问题。采用大涡模拟（LES）的概念，采用亚网格尺度（SGS）模型模拟湍流效应。采用算子分裂法求解改进后的NSE。应用该模型对具有表面波的水下平面射流进行了三种不同情况的模拟：强波射流、弱波射流和无波射流。数值结果表明，波浪增强了射流与周围流体的混合，并引起射流的周期性偏转。再循环的大小约为1.5~2.4 h（水深）。纯射流和波浪条件下射流在建立流区的速度分布都是自相似的。Re数为1025和2050的纯动量射流的扩散特征常数α分别为0.100和0.105。弱波和强波条件下射流的α值从0.130增加到0.147，表明波对射流的混合和稀释特性有明显的影响。对于纯射流和带波射流，数值计算结果与实验数据吻合较好。
When wastewater is discharged into a coastal area through an outfall system, it will always be subjected to the action of waves. It is important to study and quantify the mixing of the discharge with the ambient water so that accurate environmental impact assessment can be made for such discharge conditions. The present work aims to study the phenomenon of a plane jet discharged into water environment with regular waves. A 3D numerical model based on the full Navier-Stokes equations (NSE) in the σ-coordinate is developed to study the present problem. Turbulence effects are modeled by a subgrid-scale (SGS) model using the concept of large eddy simulation (LES). The operator splitting method is used to solve the modified NSE. The model has been applied to the simulation of three different cases of submerged plane jets with surface waves: jet with strong waves, jet with weak waves and jet without waves. Numerical results show that the waves enhance the mixing of the jet with the ambient fluid, and cause a periodic deflection of the jet. The size of the re-circulation is about 1.5～2.4 h (water depth) . The velocity profile of the jet is self-similar in the zone of established flow for both the pure jet and jet in wave circumstances. The spreading characteristic constant α is 0.100 and 0.105 for pure momentum jets with Re numbers 1025 and 2050. The value of α increases from 0.130 to 0.147 for a jet in weak and strong wave circumstances, showing that waves have an obvious effect on the mixing and dilution properties of jets. Numerical results are in good agreement with the experimental data for the cases of pure jets and jets with waves.