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arXiv 1708.03039physics.flu-dyn
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分离边缘自相似逆压梯度湍流边界层的直接数值模拟

Direct numerical simulation of a self-similar adverse pressure gradient turbulent boundary layer at the verge of separation

Vassili Kitsios, Atsushi Sekimoto, Callum Atkinson, Juan A. Sillero, Guillem Borrell, Ayse G. Gungor, Javier Jiménez, Julio Soria

摘要:

本文给出了分离边缘自相似逆压梯度湍流边界层(TBL)直接数值模拟(DNS)的统计特性。APG TBL具有从$Re_{δ_2}=570$到$13800$的基于动量厚度的雷诺数范围,具有从$Re_{δ_2} = 10000$到$12300$的自相似区域。在该区域内,平均无量纲压力梯度参数$β=39$,其中对于单位密度$β=δ_1 P_e^\prime / τ_w$,$δ_1$为位移厚度,$τ_w$为壁面处的平均剪切应力,以及$P_e^\prime$为远场压力梯度。将该流动与之前的零压力梯度(ZPG)和类似雷诺数的温和APG TBL($β=1$)结果进行比较。所有流量都是通过平面上TBL的DNS产生的,远场边界条件适合于应用所需的压力梯度。自相似性的条件,以及适当的长度和速度尺度。的平均值和雷诺应力分布崩溃时,无量纲的基础上,这些长度和速度尺度。随着压力梯度的增加,流动的性质不太像ZPG TBL,而更类似于自由剪切层。

英文摘要:

The statistical properties are presented for the direct numerical simulation (DNS) of a self-similar adverse pressure gradient (APG) turbulent boundary layer (TBL) at the verge of separation. The APG TBL has a momentum thickness based Reynolds number range from $Re_{δ_2}=570$ to $13800$, with a self-similar region from $Re_{δ_2} = 10000$ to $12300$. Within this domain the average non-dimensional pressure gradient parameter $β=39$, where for a unit density $β=δ_1 P_e^\prime / τ_w$, with $δ_1$ the displacement thickness, $τ_w$ the mean shear stress at the wall, and $P_e^\prime$ the farfield pressure gradient. This flow is compared to previous zero pressure gradient (ZPG) and mild APG TBL ($β=1$) results of similar Reynolds number. All flows are generated via the DNS of a TBL on a flat surface with farfield boundary conditions tailored to apply the desired pressure gradient. The conditions for self-similarity, and the appropriate length and velocity scales are derived. The mean and Reynolds stress profiles are shown to collapse when non-dimensionalised on the basis of these length and velocity scales. As the pressure gradient increases the flow has properties less like a ZPG TBL and more akin to a free shear layer.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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