Large-Scale Vortical Structures Produced by an Impinging Density Jet in Shallow Crossflow
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摘要: 采用RNG湍流模型对浅水横流中异重冲击射流的大尺度涡结构进行了详细的数值研究．分析了冲击区滞止点上游壁面涡结构和近区Scarf涡结构的尺度、形成机理和演化特征．计算得到了上游壁面涡的特征尺度，结果表明上游壁面涡具有高度的三维性，其特征尺度依赖于流速比和环境水深．近区Sarf涡结构对横流冲击射流的横向浓度分布具有重要的影响．当流速比相对较小时，在底层壁射流与环境横流的横向边界附近出现明显的高浓度聚集现象，计算结果表明Scarf涡结构对这一高浓度聚集区的形成起主导作用．Abstract: The large-scale vortical structures produced by an impinging density jet in shallow crossflow were numerically investigated in detail using RNG turbulence model.The scales,formation mechanism and evolution feature of the upstream wall vortex in relation to stagnation point and the Scarf vortex in near field were analyzed.The computed characteristic scales of the upstream vortex show distinguished three-dimensionality and vary with the velocity ratio and the water depth.The Scarf vortex in the near field plays an important role in the lateral concentration distributions of the impinging jet in crossflow.When the velocity ratio is relatively small,there exists a distinct lateral high concentration aggregation zone at the lateral edge between the bottom layer wall jet and the ambient crossflow,which is dominated by the Scarf vortex in the near field.
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Key words:
- impinging jet /
- crossflow /
- large-scale vortical structure /
- concentration distribution
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