| 武周虎,武文,路成刚.河流混合污染物浓度二维移流扩散方程的解析计算及其简化计算的条件Ⅱ：顺直河流考虑边界反射[J].水利学报,2009,40(9): |
| 河流混合污染物浓度二维移流扩散方程的解析计算及其简化计算的条件Ⅱ：顺直河流考虑边界反射 |
| Analytical calculation of the two dimensional advection diffusion equation for pollutant mixing in river and conditions for simplification Ⅱ. Straight stream with boundary reflection |
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| 中文关键词: 移流扩散方程 二维解析方法 浓度分布 边界反射 修正贝克来数 均匀混合距离 简化条件 |
| 英文关键词: advection diffusion equation two dimensional analytical solution pollutantconcentration distribution boundary reflection modified Peclet number distance of fully uniform mixing simplification condition |
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| 中文摘要: |
| 在保守物质恒定连续点源条件下，从包含河流纵向扩散项的二维移流扩散方程解析解出发，考虑两岸边界反射作用，给出了河流污染物浓度的二维解析计算方法及污染物的无量纲浓度分布方程。定义了能综合反映纵向移流作用与纵向、横向扩散作用比值的修正贝克来数Pw。在Pw相等以及在相对浓度达到10^-6的精度条件下，通过数值计算给出了边界反射次数与修正贝克来数的回归关系式。当Pw≥7.5，忽略纵向扩散项的条件下，岸边排放与中心排放浓度分布的一半具有自动相似性。给出了河流污染物相对浓度分布、排放岸和对岸特征浓度点的无量纲纵坐标以及 |
| 英文摘要: |
| Based on the analytical solution of 2 D advection diffusion equation, the analytical method for calculating conservative pollutant concentration distribution in straight streams and corresponding formula for dimensionless concentration distribution, with boundary reflection being taken into account, is deduced. The modified Peclet number (Pw) comprehensively reflecting the ratio of longitudinal advection effect to transverse diffusion effect is defined. The regression relationship between boundary reflection times and Pw for relative concentration equal to 10^-6is obtained by numerical calculation. Under the condition of Pw≥7.5 and neglecting the longitudinal diffusion, the assumption that the pollutant concentration distribution discharged from the bank side is similar to that of the half side discharged from the river center is demonstrated. Furthermore, the relative concentration distribution of pollutant and the dimensionless transverse coordinates of the characteristic concentration points at the bank exhausting pollutant and its opposite bank, as well as the relationship between Pw and the dimensionless distance for pollutant full section uniformly mixed are given. It is concluded that the Pw can be used as the discrimination of the simplification of advection diffusion equation and the conditions of simplification, in consideration of boundary reflection, can be deduced. |
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