The jet formation of gas inhomogeneities under the impact of a planar shock wave is an interesting phenomenon that is closely related to shock convergence. In this study, a series of heavy gas inhomogeneities with very simple geometries (square, rectangle, circle, and triangle) are numerically reproduced to trace the source of the jet formation. Special attention is given to the wave patterns that lead to the formation of specific jet forms. The shock-accelerated multicomponent flow is simulated by solving inviscid compressible Euler equations. An up-wind characteristic space-time conservation element and solution element scheme is adopted, and a five-equation model is used to treat the gas interface. The jet types that emerge in the experimental images are explained based on the numerical results, and a typical shock pattern that ensures the jet formation is uncovered. It is found that, physically, the jet is initiated by the impact of the internal Mach stem, and the jet growth is nourished by the high speed gas flow induced by this Mach stem. The width of the jet is determined by the height of the internal Mach stem. Geometrically, a focal wedge enveloped by slip lines emerges in the gas inhomogeneity, in which the gas is accelerated. It is found that the existence of the focal wedge and the coordinates of the wedge tip can be used as qualitative criteria to illustrate the mechanism of the jet formation. These criteria provide a more intuitive basis for understanding the direction, scale, and process of jet formation.
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February 2019
Research Article|
February 05 2019
Numerical study on the jet formation of simple-geometry heavy gas inhomogeneities
E. Fan
;
E. Fan
1
The Hong Kong Polytechnic University, Department of Mechanical Engineering
, Hung Hom, Kowloon, Hong Kong, People’s Republic of China
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Ben Guan;
Ben Guan
a)
1
The Hong Kong Polytechnic University, Department of Mechanical Engineering
, Hung Hom, Kowloon, Hong Kong, People’s Republic of China
a)Author to whom correspondence should be addressed: guanben@mail.ustc.edu.cn
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Chih-Yung Wen;
Chih-Yung Wen
a)
1
The Hong Kong Polytechnic University, Department of Mechanical Engineering
, Hung Hom, Kowloon, Hong Kong, People’s Republic of China
a)Author to whom correspondence should be addressed: guanben@mail.ustc.edu.cn
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Hua Shen
Hua Shen
2
King Abdullah University of Science and Technology (KAUST), Extreme Computing Research Center (ECRC), Computer, Electrical and Mathematical Sciences & Engineering (CEMSE)
, Thuwal 23955-6900, Saudi Arabia
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a)Author to whom correspondence should be addressed: guanben@mail.ustc.edu.cn
Physics of Fluids 31, 026103 (2019)
Article history
Received:
November 29 2018
Accepted:
January 14 2019
Citation
E. Fan, Ben Guan, Chih-Yung Wen, Hua Shen; Numerical study on the jet formation of simple-geometry heavy gas inhomogeneities. Physics of Fluids 1 February 2019; 31 (2): 026103. https://doi.org/10.1063/1.5083636
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