arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1706.07214physics.flu-dyn
收藏

涡环诱导初始静止液滴合并时的内部混合

Vortex-Ring-Induced Internal Mixing Upon the Coalescence of Initially Stationary Droplets

Xi Xia, Chengming He, Dehai Yu, Jiaquan Zhao, Peng Zhang

摘要:

本研究采用改进的流体体积法和自适应网格加密算法,数值研究了两个初始静止的大小不等的液滴合并后的内部射流混合。内部射流的出现归因于主涡环的形成,因为射流状结构显示出与合并液滴内部的主涡环的强相关性。通过跟踪主涡环及其环流的演变,我们确定了两个机制,是必不可少的内部射流的形成:涡环的增长和涡环分离。认识到涡环诱导射流的表现形式在物理上依赖于涡环的对流和粘性耗散之间的竞争,我们进一步开发和证实了基于涡环的雷诺数准则来解释在不同的Ohnesorge数和尺寸比的内部射流的发生。对于具有明显射流形成的合并液滴,射流形成后的平均混合速率随涡环雷诺数单调增加,因此涡环雷诺数可作为射流强度的近似度量。在这方面,更强的内部射流负责增强合并液滴的混合。

英文摘要:

This study employs an improved volume of fluid method and adaptive mesh refinement algorithm to numerically investigate the internal jet-like mixing upon the coalescence of two initially stationary droplets of unequal sizes. The emergence of the internal jet is attributed to the formation of a main vortex ring, as the jet-like structure shows a strong correlation with the main vortex ring inside the merged droplet. By tracking the evolution of the main vortex ring together with its circulation, we identified two mechanisms that are essential to the internal-jet formation: the vortex-ring growth and the vortex-ring detachment. Recognizing that the manifestation of the vortex-ring-induced jet physically relies on the competition between the convection and viscous dissipation of the vortex ring, we further developed and substantiated a vortex-ring-based Reynolds number criterion to interpret the occurrence of the internal jet at various Ohnesorge numbers and size ratios. For the merged droplet with apparent jet formation, the average mixing rate after jet formation increases monotonically with the vortex-ring Reynolds number, which therefore serves as an approximate measure of the jet strength. In this respect, stronger internal jet is responsible for enhanced mixing of the merged droplet.

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。

↑