arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2407.00992physics.flu-dyn
收藏

液-液两相Taylor-Couette湍流中的湍流调制

Turbulence modulation in liquid-liquid two-phase Taylor-Couette turbulence

Jinghong Su, Cheng Wang, Yi-bao Zhang, Fan Xu, Junwu Wang, Chao Sun

AI总结:

本研究通过界面分辨直接数值模拟,探究不同属性液滴对两相Taylor-Couette湍流的调制机制,揭示了液滴黏度、密度对阻力及湍动能输运的不同影响规律,为两相流湍流调控提供新认知。

摘要:

我们采用基于volume-of-fluid(流体体积)方法的界面分辨三维直接数值模拟,研究了系统雷诺数为6000、系统韦伯数为10时,分散相与连续相的两相界面、黏度比及密度比对两相Taylor-Couette湍流流动统计特性的耦合效应。研究聚焦四种不同场景:中性液滴、低黏度液滴、轻质液滴以及低黏度轻质液滴。我们发现,中性液滴和低黏度液滴主要通过两相界面起到增阻作用,而轻质液滴因雷诺应力的密度依赖性,通过显著降低雷诺应力来减小系统阻力。此外,低黏度轻质液滴可进一步减弱内圆柱附近的动量输运,并隐性降低雷诺应力,从而实现更显著的减阻效果。虽然界面张力会增强湍动能(TKE)输运,但对于中性液滴和低黏度液滴而言,增阻效果与TKE输运的相关性并不强。轻质液滴主要通过削弱雷诺应力来减小生成项,而两相间的密度差则会提升内壁附近的TKE输运。因此,耗散率的降低主要归因于湍流生成的减弱,进而产生减阻效应。对于低黏度轻质液滴,生成项进一步减小,这主要是因为它们对雷诺应力的削弱作用更强,同时黏度的降低减弱了密度差对内圆柱附近TKE输运的贡献,使得耗散率的下降更为明显,最终带来更强的减阻效果。我们的研究结果为两相流中的湍流调制提供了新的见解。

英文摘要:

We investigate the coupling effects of the two-phase interface, viscosity ratio, and density ratio of the dispersed phase to the continuous phase on the flow statistics in two-phase Taylor-Couette turbulence at a system Reynolds number of 6000 and a system Weber number of 10 using interface-resolved three-dimensional direct numerical simulations with the volume-of-fluid method. Our study focuses on four different scenarios: neutral droplets, low-viscosity droplets, light droplets, and low-viscosity light droplets. We find that neutral droplets and low-viscosity droplets primarily contribute to drag enhancement through the two-phase interface, while light droplets reduce the system's drag by explicitly reducing Reynolds stress due to the density dependence of Reynolds stress. Additionally, low-viscosity light droplets contribute to greater drag reduction by further reducing momentum transport near the inner cylinder and implicitly reducing Reynolds stress. While interfacial tension enhances turbulent kinetic energy (TKE) transport, drag enhancement is not strongly correlated with TKE transport for both neutral droplets and low-viscosity droplets. Light droplets primarily reduce the production term by diminishing Reynolds stress, whereas the density contrast between the phases boosts TKE transport near the inner wall. Therefore, the reduction in the dissipation rate is predominantly attributed to decreased turbulence production, causing drag reduction. For low-viscosity light droplets, the production term diminishes further, primarily due to their greater reduction in Reynolds stress, while reduced viscosity weakens the density difference's contribution to TKE transport near the inner cylinder, resulting in a more pronounced reduction in the dissipation rate and consequently stronger drag reduction. Our findings provide new insights into the turbulence modulation in two-phase flow.

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。

↑