Nonequilibrium and morphological characterizations of Kelvin-Helmholtz instability in compressible flows

We investigate the effects of viscosity and heat conduction on the onset and growth of Kelvin-Helmholtz instability (KHI) via an efficient discrete Boltzmann model. Technically, two effective approaches are presented to quantitatively analyze and understand the configurations and kinetic processes....

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Bibliographic Details
Published in:Frontiers of physics 2019-08, Vol.14 (4), p.43602, Article 43602
Main Authors: Gan, Yan-Biao, Xu, Ai-Guo, Zhang, Guang-Cai, Lin, Chuan-Dong, Lai, Hui-Lin, Liu, Zhi-Peng
Format: Article
Language:English
Subjects:
Applied physics
Astronomy
Astrophysics
Astrophysics and Cosmology
Atomic
Compressible flow
Computational mathematics
Condensed Matter Physics
Conduction heating
Conductive heat transfer
discrete Boltzmann method
Energy
Engineering
Fluids
Interfaces
Investigations
Kelvin-Helmholtz instability
Mixing layers (fluids)
Molecular
morphological characterization
Morphology
Optical and Plasma Physics
Particle and Nuclear Physics
Physics
Physics and Astronomy
Research Article
thermodynamic nonequilibrium effect
Thickness
Viscosity
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Summary:We investigate the effects of viscosity and heat conduction on the onset and growth of Kelvin-Helmholtz instability (KHI) via an efficient discrete Boltzmann model. Technically, two effective approaches are presented to quantitatively analyze and understand the configurations and kinetic processes. One is to determine the thickness of mixing layers through tracking the distributions and evolutions of the thermodynamic nonequilibrium (TNE) measures; the other is to evaluate the growth rate of KHI from the slopes of morphological functionals. Physically, it is found that the time histories of width of mixing layer, TNE intensity, and boundary length show high correlation and attain their maxima simultaneously. The viscosity effects are twofold, stabilize the KHI, and enhance both the local and global TNE intensities. Contrary to the monotonically inhibiting effects of viscosity, the heat conduction effects firstly refrain then enhance the evolution afterwards. The physical reasons are analyzed and presented.
ISSN:2095-0462
2095-0470
DOI:10.1007/s11467-019-0885-4