Shock Waves in Granular Gases

Continuum modelling of shock waves through granular gases and the role of statistical fluctuations

10.1063/1.4967626 ◽

2016 ◽

Author(s):

Nick Sirmas ◽

Matei I. Radulescu

Keyword(s):

Shock Waves ◽

Granular Gases ◽

Statistical Fluctuations ◽

Continuum Modelling

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Structure of velocity distributions in shock waves in granular gases with extension to molecular gases

Physical Review E ◽

10.1103/physreve.94.022905 ◽

2016 ◽

Vol 94 (2) ◽

Cited By ~ 4

Author(s):

A. Vilquin ◽

J. F. Boudet ◽

H. Kellay

Keyword(s):

Shock Waves ◽

Granular Gases ◽

Molecular Gases

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Structure and stability of shock waves in granular gases

Journal of Fluid Mechanics ◽

10.1017/jfm.2019.345 ◽

2019 ◽

Vol 873 ◽

pp. 568-607 ◽

Cited By ~ 3

Author(s):

Nick Sirmas ◽

Matei I. Radulescu

Keyword(s):

Shock Waves ◽

Molecular Dynamic ◽

Travelling Wave ◽

Granular Gases ◽

Shock Formation ◽

Molecular Dynamic Simulations ◽

Dynamic Simulations ◽

Relaxation Effects ◽

Molecular Noise ◽

Dynamics Simulations

Previous experiments have revealed that shock waves driven through dissipative media may become unstable, for example, in granular gases, and in molecular gases undergoing strong relaxation effects. The current paper addresses this problem of shock stability at the Euler and Navier–Stokes continuum levels in a system of disks (two-dimensional) undergoing activated inelastic collisions. The dynamics of shock formation and stability is found to be in very good agreement with earlier molecular dynamic simulations (Sirmas & Radulescu, Phys. Rev. E, vol. 91, 2015, 023003). It was found that the modelling of shock instability requires the introduction of molecular noise for its development and sustenance. This is confirmed in two stability problems. In the first, the evolution of shock formation dynamics is monitored without noise, with only initial noise and with continuous molecular noise. Only the latter reproduces the results of shock instability of molecular dynamics simulations. In the second problem, the steady travelling wave solution is obtained for the shock structure in the inviscid and viscous limits and its nonlinear stability is studied with and without molecular fluctuations, again showing that instability can be sustained only in the presence of fluctuations. The continuum results show that instability takes the form of a rippled front of a wavelength comparable with the relaxation thickness of the steady shock wave, at scales at which molecular fluctuations become important, in excellent agreement with the molecular dynamic simulations.

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Capturing shock waves in inelastic granular gases

Journal of Computational Physics ◽

10.1016/j.jcp.2005.04.004 ◽

2005 ◽

Vol 209 (2) ◽

pp. 787-795 ◽

Cited By ~ 14

Author(s):

Susana Serna ◽

Antonio Marquina

Keyword(s):

Shock Waves ◽

Granular Gases

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Investigation of shock-wave deformation history from recovered structure

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143754 ◽

1986 ◽

Vol 44 ◽

pp. 434-435

Author(s):

M.A. Mogilevsky ◽

L.S. Bushnev

Keyword(s):

Shock Wave ◽

Plastic Deformation ◽

Dislocation Density ◽

Shock Waves ◽

Shock Front ◽

Single Crystals ◽

Residual Deformation ◽

Deformation Structure ◽

Deformation History ◽

Deformation Velocity

Single crystals of Al were loaded by 15 to 40 GPa shock waves at 77 K with a pulse duration of 1.0 to 0.5 μs and a residual deformation of ∼1%. The analysis of deformation structure peculiarities allows the deformation history to be re-established.After a 20 to 40 GPa loading the dislocation density in the recovered samples was about 1010 cm-2. By measuring the thickness of the 40 GPa shock front in Al, a plastic deformation velocity of 1.07 x 108 s-1 is obtained, from where the moving dislocation density at the front is 7 x 1010 cm-2. A very small part of dislocations moves during the whole time of compression, i.e. a total dislocation density at the front must be in excess of this value by one or two orders. Consequently, due to extremely high stresses, at the front there exists a very unstable structure which is rearranged later with a noticeable decrease in dislocation density.

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