Compressibility effects on statistics and coherent structures of compressible turbulent mixing layers

Wang, Xiaoning1,2,3; Wang, Jianchun1,2,3; Chen, Shiyi1,2,3

2022-08-30

10.1017/jfm.2022.660

JOURNAL OF FLUID MECHANICS   Impact Factor & Quartile

0022-1120

1469-7645

The effects of compressibility on the statistics and coherent structures of a temporally developing mixing layer are studied using numerical simulations at convective Mach numbers ranging from M-c = 0.2 to 1.8 and at Taylor Reynolds numbers up to 290. As the convective Mach number increases, the streamwise dissipation becomes more effective to suppress the turbulent kinetic energy. At M-c = 1.8, the streamwise dissipation increases much faster than the other two components in the transition region, even larger than pressure-strain redistribution, correlating with the streamwise elongated vortical structures at a higher level of compressibility. We confirm the existence of the large-scale high- and low-speed structures in the mixing layers, which accompany the spanwise Kelvin-Helmholtz rollers at low convective Mach number and dominate the mixing layer at higher convective Mach number. Conditional statistics demonstrate that the large-scale low-speed structures are lifted upwards by a pair of counter-rotating quasi-streamwise rollers flanking the structures. The small-scale vortical structures have an apparent preference for clustering into the top of the low-speed regions, which is directly associated with high-shearing motions on top of the low-speed structures. The high-speed structures statistically exhibit central symmetry with the low-speed structures. The statistics and dynamics of large-scale high- and low-speed structures in the compressible mixing layers resemble those in the outer region of the turbulent boundary layers, which reveals the universality of the large-scale structures in free shear and wall-bounded turbulence. A conceptual model is introduced for the large-scale high- and low-speed structures in turbulent mixing layers.

shear layer turbulence turbulence simulation

SCI

English

First ; Corresponding

National Natural Science Foundation of China (NSFC)["91952104","92052301","12172161","12161141017"] ; National Numerical Windtunnel Project[NNW2019ZT1-A04] ; NSFC Basic Science Center Program[11988102] ; Shenzhen Science and Technology Program[KQTD20180411143441009] ; Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou)[GML2019ZD0103] ; Department of Science and Technology of Guangdong Province[2019B21203001]

Mechanics ; Physics

Mechanics ; Physics, Fluids & Plasmas

WOS:000847368000001

CAMBRIDGE UNIV PRESS

ENGINEERING

Web of Science

1.Southern Univ Sci & Technol, Dept Mech & Aerosp Engn, Shenzhen 518055, Peoples R China
2.Southern Marine Sci & Engn Guangdong Lab, Guangzhou 511458, Peoples R China
3.Southern Univ Sci & Technol, Guangdong Hong Kong Macao Joint Lab Data Driven F, Shenzhen 518055, Peoples R China

Wang, Xiaoning,Wang, Jianchun,Chen, Shiyi. Compressibility effects on statistics and coherent structures of compressible turbulent mixing layers[J]. JOURNAL OF FLUID MECHANICS,2022,947.

Wang, Xiaoning,Wang, Jianchun,&Chen, Shiyi.(2022).Compressibility effects on statistics and coherent structures of compressible turbulent mixing layers.JOURNAL OF FLUID MECHANICS,947.

Wang, Xiaoning,et al."Compressibility effects on statistics and coherent structures of compressible turbulent mixing layers".JOURNAL OF FLUID MECHANICS 947(2022).