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首页> 外文期刊>International Journal of Heat and Fluid Flow >Further studies on the statistics and structures of flat-plate boundary layer with passing wakes
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Further studies on the statistics and structures of flat-plate boundary layer with passing wakes

机译:带有尾流的平板边界层的统计和结构的进一步研究

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We present a numerical study of a flat-plate boundary layer with free-stream periodically passing planar wakes without external pressure gradients from Re_θ = 80 to fully turbulent. Two direct numerical simulations were performed on the same flow with slightly different simulations parameters. In the constrained simulation design, the wakes are restricted to six boundary layer thicknesses above the wall at the inlet, while in the other design the wakes are un-constrained. Boundary layer statistics before, during and after transition are thoroughly evaluated through comparison with theoretical and experimental data of the zero-pressure gradient flat-plate boundary layer. Three-dimensional flow visualizations reveal the instant and location of breakdown events. Negative streaks are not of the shape of a rectangular box, rather, their wedged shape narrows towards the downstream passing wake and their strength diminishes towards the wall and towards the upstream direction. Matured turbulent spots have arrowheads directed upstream. Despite the intermittency of the passing wake disturbances, statistics in the early transitional region exhibit characteristics in agreement with previous studies on boundary layer. Statistics in the turbulent boundary layers differ from the canonical case only mildly near the outer edge.
机译:我们提出了一个平板边界层的数值研究,该边界层具有自由流动的周期性通过平面尾流,而没有从Re_θ= 80到完全湍流的外部压力梯度。在相同的流上执行了两个直接数值模拟,模拟参数略有不同。在受限的模拟设计中,尾流被限制为入口处壁上方六层边界层的厚度,而在其他设计中,尾流不受限制。通过与零压力梯度平板边界层的理论和实验数据进行比较,彻底评估了过渡之前,之中和之后的边界层统计数据。三维流动可视化显示故障事件的即时和位置。负条纹不是矩形框的形状,而是其楔形朝向下游经过的尾流变窄,并且其强度朝着壁和朝上游的方向减小。成熟的湍流点的箭头指向上游。尽管经过的尾流扰动是间歇性的,但早期过渡区的统计数据仍具有与先前边界层研究一致的特征。湍流边界层的统计量与典型情况仅在外边缘略有不同。

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