含苦草水流紊流结构典型剖面的象限分析  

Quadrant analysis of the typical profile of turbulence structure in flow with Vallisneria natans

作　　者：张英豪[1,2] 赖锡军[1] 姜加虎[1] 

机构地区：[1]中国科学院南京地理与湖泊研究所中国科学院流域地理学重点实验室,南京210008 [2]中国科学院大学,北京100049

出　　处：《水动力学研究与进展（A辑）》2015年第5期526-532,共7页Chinese Journal of Hydrodynamics

基　　金：国家重点基础研究发展计划(973计划)资助项目(2012CB417000);国家自然科学基金(41071021)~~

摘　　要：该文以含苦草水流的实验室水槽实验数据为基础,选取典型流速剖面,利用象限分析法,从紊流质点的角度分析了含苦草水流的动量传输特征。分析发现,苦草冠层顶部附近水流紊动掺混剧烈,雷诺应力在冠顶处达到最大值,且水流在冠顶以上及以下区域分别以"喷射"与"下扫"流态为主;冠层内部,水流紊动掺混明显减弱,雷诺应力较小,受时均流速逆梯度的影响,雷诺应力出现负值及局部最大值,且水流在雷诺应力局部最大值出现位置以上及以下区域分别以"外向交互"与"内向交互"流态为主。冠顶附近水流强烈的紊动掺混决定了整个剖面紊流的动量传输特征,且苦草冠顶以下所形成的下扫流有利于水体中黏性泥沙的沉积,降低水体浊度。Based on the flume experimental data of flow with Vallisneria natans in laboratory. The quadrant analysis is used to explore the characteristics of momentum transport in vegetated flow by selecting typical velocity profile. It is found that strong turbulent mixing exists around the top ofV. natans canopy, and the Reynolds stress reaches its maximum at the top of canopy. In the regions above and below the top of V. natans canopy, the flow is dominated by the ＂ejection＂ event and ＂sweep＂ event respectively. Within the canopy, the turbulent mixing of flow is greatly weakened, and the Reynolds stress is small relatively to the canopy interface. Influenced by the counter gradient of mean velocity, negative Reynolds stress and a local stress maximum occur within the canopy, and the flow is dominated by ＂outwards＂ event and ＂inwards＂ event above and below the location where local stress maximum occurs, respectively. The strong turbulent mixing around the top of V. natans canopy determines the characteristics of momentum transport in the flow profile, and the sweep event generated below the canopy interface benefits the deposition of fine sediment and reduces the water turbidity.

关 键 词：水生植被 紊流结构 雷诺应力 象限分析 

分 类 号：TV143[水利工程—水力学及河流动力学]