Effects of Atwood number and stratification parameter on compressible multi-mode Rayleigh-Taylor instability
Effects of Atwood number and stratification parameter on compressible multi-mode Rayleigh-Taylor instability
复制标题
阿特伍德数和分层参数对可压缩多模瑞利-泰勒不稳定性的影响
DOI：
10.1063/5.0071437
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发表时间：
2021-11-01
影响因子：
4.6
通讯作者：
Wang, Jianchun
中科院分区：
文献类型：
--
作者：
Luo, Tengfei;Wang, Jianchun
本研究数值分析了不同阿特伍德数 (A(t)) 和分层参数 (Sr) 下对应于不同水平的流动压缩性的二维 (2D) 可压缩多模瑞利-泰勒不稳定性。研究发现，在小A(t)时，由于密度分层，气泡厚度的增长随着Sr的增加而受到抑制，而在大A(t)时，由于膨胀和压缩运动，气泡厚度的增长得到增强。在任意 A(t) 下，气泡与尖峰厚度之比随着 Sr 的增加而增加。在不同的阿特伍德数下，流动压缩性对分子混合分数、泰勒雷诺数、湍流马赫数和速度散度统计的影响是相似的。通过增加 Sr 和 A(t) 可以增强膨胀和压缩运动。混合层内膨胀运动较强，而混合层外则普遍存在压缩运动，可形成促进气泡向上运动的力。归一化后，平均浓度、平均温度和速度均方根的分布在不同分层参数下可以相互重叠，这证明了二维可压缩瑞利-泰勒（RT）湍流的自相似性。密度分层削弱了势能到动能的转换，而流动压缩性增强了大Sr值下的压力膨胀功。目前的结果有助于可压缩RT湍流理论模型的发展。由 AIP Publishing 独家许可出版。
This study numerically analyzes the two-dimensional (2D) compressible multi-mode Rayleigh-Taylor instability at different Atwood numbers (A(t)) and stratification parameters (Sr), corresponding to the different levels of flow compressibility. It is found that the growth of bubble thickness is suppressed with the increase in Sr due to the density stratification at small A(t), whereas it is enhanced at large A(t), because of the expansion and compression motions. The ratio of the bubble to spike thickness increases with the increase in Sr at any A(t). The effects of the flow compressibility on the molecular mixing fraction, Taylor Reynolds number, turbulent Mach number, and velocity divergence statistics are similar at different Atwood numbers. The expansion and compression motions are enhanced by increasing the Sr and A(t). The expansion motions are relatively strong in the mixing layer, whereas the compression motions are prevalent outside the mixing layer, which may form a force promoting the upward movement of the bubble. The profiles of mean concentration, mean temperature, and root mean square of velocities can overlap with each other at different stratification parameters after normalization, which demonstrates the self-similarity of the 2D compressible Rayleigh-Taylor (RT) turbulence. The density stratification weakens the conversion from potential energy to kinetic energy, while the flow compressibility enhances the pressure-dilatation work at large values of Sr. The present results can help in the development of theoretical models of compressible RT turbulence. Published under an exclusive license by AIP Publishing.