| 刘春晶,曹文洪,耿旭,许琳娟.粗化床面非均匀沙推移质运动扩散特性研究[J].中国水利水电科学研究院学报,2021,19(1):130-137,147 |
| 粗化床面非均匀沙推移质运动扩散特性研究 |
| Diffusive behavior of non-uniform bedload particles over an armored bed surface |
| 投稿时间：2020-07-03 |
| DOI：10.13244/j.cnki.jiwhr.20200112 |
| 中文关键词: 粗化床面 非均匀沙 推移质 扩散特性 水槽试验 |
| 英文关键词:armored bed surface non-uniform sediment bedload transport diffusion characteristics flume experiment |
| 基金项目:国家自然科学基金项目（5167091342）；中国水科院基本科研业务费项目（SE0145B572017，SE0145B482016） |
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| 中文摘要: |
| 对泥沙颗粒运动规律的把握是准确估算推移质输沙率的基础。本文开展了粗化床面条件下的水槽试验，分析了非均匀沙颗粒的均方位移和速度自相关系数变化，并与已有均匀沙试验进行了对比。结果表明，粗化床面存在着由单个或多个粗颗粒组成的粗化结构体，形成比平整床面更复杂的底部边界，粗化结构体对泥沙颗粒运动造成较大影响，颗粒在运动过程中与水流动量交换强度大，泥沙颗粒运动与均匀沙试验“类弹道扩散”存在一定差异；受床面结构影响，部分颗粒表现出较强的横向运动，颗粒的横向扩散特性与流向扩散特性类似。与均匀沙平整床面不同，粗化床面上颗粒运动可能会相应改变床面结构，从而改变水流底部边界条件，进而对泥沙颗粒运动造成影响，泥沙颗粒运动存在较明显的记忆效应和反常扩散现象。 |
| 英文摘要: |
| The law of grain-scale bedload particle movement is fundamental to estimate the bedload transport rate accurately. In this paper, we conduct the flume test under rough bed conditions, analyze the mean square displacement and autocorrelation velocities of non-uniform sediment particles under armored bed conditions,and compare them with existing uniform sediment tests. The results show armored structures are composed of single or multiple coarse particles in the flume bed, forming a more complicated bottom boundary than the flatbed surface. The armored structure has a significant impact on sediment movement, the momentum exchange between flow and particles is more extensive than in flatbed, and bedload particles are not as "ballistic-like" movement in the flatbed. Affected by the bed surface structure, some particles show strong lateral movement, and the particles' lateral diffusion characteristics and the flow direction diffusion characteristics are similar. Unlike the uniform sand in the flatbed bed surface, the particle movement on the coarsened surface may change the bed surface structure,therefore changing the bottom boundary conditions and then affecting sediment particles' movement. Moreover,it has a more obvious memory effect and anomalous diffusion phenomenon in armored bed than in the flatbed. |
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