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力学讲堂 | 肖左利副教授:RM和RT不稳定性及湍流混合中的能量和涡动力学过程

发布时间:2018-05-24  点击次数:1406

主  办:力学系与湍流重点实验室
报告人:肖左利副教授
时  间:5月18日 周五 中午12:00
地  点:力学楼434室
主持人:杨莹 教授

 


 

报告内容摘要:

 


The Richtmyer-Meshkov instability (RMI) and Rayleigh-Taylor instability (RTI) induced mixing flows in a rectangular shock tube are numerically investigated based on an in-house high-order turbulence solver (HOTS). Focus is placed on the analysis of the scale-to-scale energy transfer of kinetic energy both in Fourier and physical spaces. It is the nonlinear advection flux that predominates over other components for the total spectral energy flux across a given scale. The kinetic energy injected from the perturbation scales is transferred both backward to larger scales and forward to larger scales in an average sense with the IMZ at early times, and is mainly passed down into small scales at the late stage. The energy flux across the upper limit of the initial perturbation scales due to the work done by the coarse-grained strain rate against the subgrid-scale (SGS) stress is further studied in physical space using a filtering approach with particular emphasis on the physical origin of the scale-to-scale kinetic energy transfer process. It is found that pointwise kinetic energy transfer due to the SGS stress effect is highly associated with the local structures in the IMZ. At early times the positive SGS fluxes occur dominantly in spike regions while the negative ones in bubble regions as well as the central region of the IMZ. In the late stage, however, only forward transfer of kinetic energy can be observed, which takes place in the spike-side regions. Moreover, it turns out that the mean SGS energy flux is mainly ascribed to the component in the direction of shock wave propagation. The energy and vortex dynamics of interfacial fluid instability in spherical geometry will also be discussed.
 
报告人简介:

 


 
肖左利副教授,1998年天津大学力学与工程测试系毕业;2001年天津大学力学与工程测试系流体力学研究生毕业;2001年9月—2008年8月赴美国留学,2003年获得南加州大学航空航天系硕士学位,2008年获得约翰霍普金斯大学机械工程系博士学位。
 
2008年9月—2014年8月 北京大学工学院力学与工程科学系新体制特聘研究员、博士生导师,2014年9月—现在 北京大学工学院力学与工程科学系新体制长聘副教授、研究员、博士生导师。
 
科研方向:湍流理论、湍流模型和大涡模拟、直接数值模拟、流体界面不稳定性及混合、计算流体力学、大规模并行计算等。
 
 
 
 
 
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