中文摘要：

为分析水流交汇区污染物输移扩散规律，开展了交汇区污染物浓度分布规律的实验和数值模拟研究。建立了交汇区污染物扩散的水气两相流数学模型，并采用实验结果进行验证，对交汇区不同流量、动量和交汇角情况进行实验和数值模拟研究。结果表明：含高浓度污染物的支流汇入干流后，在交汇口下游支流侧形成较长的污染带，且支流与于流的交汇角和流量比（动量比）越小，污染带越狭长；在污染带范围内，污染物浓度梯度较大；污染物分布主要受随流输移和扩散的综合作用影响，其中在交汇区污染物的扩散作用明显。

英文摘要：

In order to analyze transportation and diffusion characteristics of contaminants at flow confluence, this pa- per presents the results of a series of experiments that were conducted and the numerical simulation study for probing distribution rules at flow confluence. A two-phase flow model applicable to confluences was established, and it was verified by experimental results. Experiments and numerical simulation were performed for different conditions. The results indicate that ： A long and narrow contaminated zone is formed near the tributary side ; and, the smaller junction angle and flow ratio （momentum ratio） are narrower with contaminated zone; within the contaminated zone, the gradi- ent of concentration is great; and, contaminants distribution at the confluence is mainly determined by the effects of transportation and diffusion. These study results can provide a scientific basis for environmental evaluation, manage- ment and pollution control of river confluence.