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  • [2012-06-08]

    Breakthrough in high Mach number compressible turbulence studies

A research team of Peking University has recently achieved breakthrough in the scaling and statistical properties studies of high Mach number compressible turbulence. Led by Shiyi Chen, professor in the State Key Laboratory for Turbulence and Complex Systems (SKLTCS), and Xiantu He, physicist in the Center for Applied Physics and Technology (CAPT), the team obtained accurate high Mach number turbulent fields with high-accuracy numerical simulation and analyzed the underlying physical process in the compressible turbulence. The results were published by Physical Review Letters on May 25, 2012.

High Mach number turbulence is of great importance to a large number of industrial applications and natural phenomena, including high-temperature reactive flows, combustion, transonic and hypersonic aircrafts, space exploration and astrophysics. Recently, the high Mach number turbulence and its mechanism become a hot area for turbulence research.

The Shockwave-Vortex Structure in compressible turbulence

The research method of high Mach number compressible turbulence is quite different from that of weakly compressible and incompressible turbulence. Usually, the influence caused by the variation of density is neglected in the research of weakly compressible turbulence, therefore the models for incompressible turbulence studies are also suitable for weakly compressible turbulence research. However, those models are not suitable for the modest and high Mach number turbulence, of which compressibility is obvious. For a long time, scientists haven’t found efficient tools to study and analyze the high Mach number compressible turbulence.
Professor Shiyi Chen and his group obtained the accurate high Mach number turbulent fields by numerical simulation with high accuracy. In addition, with the multi-process decomposition, they found the scaling of the shear and dilation process, and the statistic properties of their interaction.

As the one-dimensional simplified model of turbulence, the statistic of the behavior of Burgers turbulence (Burgulence) is an attractive subject for physicist and mathematicians. Although scientists have realized there is some linkage between Burgers turbulence and the compressible turbulence, the strict proof for the linkage hasn’t been proposed.

Probability density function of velocity divergence
 
Professor Shiyi Chen and his group analyzed the dilation equations for Burgers turbulence and compressible turbulence, and showed the influence of pressure on the probability density function of the dilation. So a perfect explanation for the similarities and difference between Burgers turbulence and compressible turbulence is presented.
 
"This work is an important progress in the research of turbulences, and has a far influence on the research work in the future,” said Chen.
 
This work is supported by the National Natural Science Foundation of China, the National Science and Technology Ministry under a subproject of the 973 program and CAPT of Peking University.
Other authors who contributed to the work include Jianchun Wang, Yipeng Shi, Zuoli Xiao from SKLTCS and CAPT, College of Engineering, Peking University and Lian-Ping Wang from Department of Mechanical Engineering, University of Delaware.
 
Paper cited:
Scaling and Statistics in Three-Dimensional Compressible Turbulence, Phys. Rev.Lett. 108, 214505(2012)
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