Intermittent Turbulence Characteristics in the Stokes Layer for a Transitional Reynolds Number
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摘要: 针对典型的过渡Reynolds数Re=495,以壁面的表面粗糙度为激励,用数值模拟的方法研究了Stokes层的间歇湍流特性,分别从壁面平均速度梯度、平均速度剖面以及Reynolds应力等方面进行了分析.发现平均速度剖面在一个周期的大部分相位下并不符合对数律,只有减速阶段的极少数相位处与对数律符合得较好;将Reynolds应力与不可压缩边界层的结果进行了对比,发现两者从分布上很相似,包括峰值大小及位置,但二者在湍流核心区存在较大的差异.以上特性显示出Stokes层过渡阶段间歇湍流的强非平衡性.
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关键词:
- Stokes层 /
- 过渡Reynolds数 /
- 间歇湍流 /
- 湍流特性
Abstract: The characteristics of intermittent turbulence induced by wall surface roughness in a finite Stokes layer were investigated numerically, including the velocity gradient at the wall, the velocity profile and the Reynolds stress, etc., with a transitional Reynolds number Re=495.The results show that, the velocity profile does not follow the logarithmic law in most phases, but does only in some rare phases during the decelerating stage. The comparison between the Reynolds stress and the result in the case of the incompressible boundary layer indicates that, the Reynolds stress distribution in the turbulence stage is similar to that in the case of the incompressible boundary layer, including the peak amplitude and the peak position, but there is significant discrepancy in the turbulence core region between the 2 cases. Above characteristics reveal the strong nonequilibrium behaviors of intermittent turbulence in the Stokes layer. -
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