Growth mechanism of interfacial fluid-mixing width induced by successive nonlinear wave interactions
Growth mechanism of interfacial fluid-mixing width induced by successive nonlinear wave interactions
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连续非线性波相互作用引起界面流体混合宽度的增长机制
DOI：
10.1103/physreve.103.053109
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发表时间：
2021
影响因子：
2.4
通讯作者：
Zhang Yousheng
中科院分区：
文献类型：
--
作者：
Li Haifeng;Tian Baolin;He Zhiwei;Zhang Yousheng
由诸如冲击波、稀疏波和压缩波的连续波引起的界面流体混合在工程应用中起着基本作用，例如，惯性约束聚变，以及在自然现象中，例如，超新星爆炸这些波浪将不均匀、不稳定的外力带入混合区，导致复杂的混合过程。通过将湍流场分解为平均场和脉动场，分析了混合宽度的增长率。因此，增长率分为三个部分：（i）由混合区两端之间的平均速度差引起的拉伸或压缩（S（C））效应，（ii）由代表两种物质相互渗透的波动引起的渗透效应，和（iii）扩散效应，这是由分子扩散引起的，并且在高雷诺数流动中在单位阶数的施密特数下可以忽略不计。穿透效应进一步分为里希特迈尔-梅什科夫（RM）效应和瑞利-泰勒（RT）效应，前者是由早期波相互作用产生的波动引起的，后者是由混合区整体加速产生的波动引起的。在稀疏波通过期间，混合区被拉伸，而在压缩波或冲击波通过期间，混合区被压缩。为了说明这些影响，RM混合与重震的物理模型。结合S（C），RM和RT的影响，整个混合宽度的演变重组，这符合数值模拟的问题与广泛的密度比。
Interfacial fluid mixing induced by successive waves, such as shock, rarefaction, and compression waves, plays a fundamental role in engineering applications, e.g., inertial confinement fusion, and in natural phenomena, e.g., supernova explosion. These waves bring nonuniform, unsteady external forces into the mixing zone, which leads to a complex mixing process. The growth rate of the mixing width is analyzed by decomposing the turbulent flow field into the averaged field and the fluctuating counterpart. The growth rate is thus divided into three parts: (i) the stretching or compression (S(C)) effect induced by the averaged-velocity difference between two ends of the mixing zone, (ii) the penetration effect induced by the fluctuations which represent the penetration of the two species into each other, and (iii) the diffusive effect, which is induced by the molecular diffusion and is negligible in high-Reynolds-number flows at Schmidt number of order unity. The penetration effect is further divided into the Richtmyer-Meshkov (RM) effect, which is induced by fluctuations that were deposited by earlier wave interactions, and the Rayleigh-Taylor (RT) effect, which is caused by the fluctuations that arise in an overall acceleration of the mixing zone. During the passage of the rarefaction waves, the mixing zone is stretched, while during the passage of the compression waves or shock waves, the mixing zone is compressed. To illustrate these effects, a physical model of RM mixing with reshock is used. By combining the S(C), RM, and RT effects, the entire evolution of mixing width is restructured, which agrees well with numerical simulations for problems with a wide range of density ratios.