Convergent Richtmyer–Meshkov instability of heavy gas layer with perturbed inner surface

Self Cite

Section: Introductionmentioning

confidence: 99%

On shock-induced heavy-fluid-layer evolution

Luo

2021

Self Cite

“…In the spherical mixing layer, the turbulent mixing exhibited stronger anisotropy at large scales than that at small scales and the inertial sub-region of kinetic energy and density spectra also showed a Kolmogorov-like −5/3 scaling law in late time, which indicated that the turbulent scales were rarely affected by the spherical mixing layer curvature. By numerically simulating two-dimensional single-mode interfaces driven by convergent shock waves, Tang et al (2021) investigated the effects of the Atwood number on the compressibility, RT stabilization and the nonlinearity.…”

Section: Introductionmentioning

confidence: 99%

“…Experimental investigations of cylindrical converging RMI in shock tubes had been conducted by several researchers, such as Hosseini & Takayama (2005), Biamino et al (2015), Luo et al (2015Luo et al ( , 2018Luo et al ( , 2019a, Zhai et al (2017), Rodriguez et al (2017), Ding et al (2017Ding et al ( , 2019, Lei et al (2017), Li et al (2020), Vandenboomgaerde et al (2018, Courtiaud et al (2019), Sun et al (2020b) and Zou et al (2019). These experimental results are particularly helpful for the development of theory and numerical simulation.…”

Section: Introductionmentioning

confidence: 99%

Statistical characteristics of turbulent mixing in spherical and cylindrical converging Richtmyer–Meshkov instabilities

et al. 2021

In this paper, the Richtmyer–Meshkov instabilities in spherical and cylindrical converging geometries with a Mach number of approximately 1.5 are investigated by using the high resolution implicit large eddy simulation method, and the influence of the geometric effect on the turbulent mixing is investigated. The heavy fluid is sulphur hexafluoride (SF6), and the light fluid is nitrogen (N2). The shock wave converges from the heavy fluid into the light fluid. The Atwood number is 0.678. The total structured and uniform Cartesian grid node number in the main computational domain is 20483. In addition, to avoid the influence of boundary reflection, a sufficiently long sponge layer with 50 non-uniform coarse grids is added for each non-periodic boundary. Present numerical simulations have high and nonlinear initial perturbation levels, which rapidly lead to turbulent mixing in the mixing layers. Firstly, some physical-variable mean profiles, including mass fraction, Taylor Reynolds number, turbulent kinetic energy, enstrophy and helicity, are provided. Second, the mixing characteristics in the spherical and cylindrical turbulent mixing layers are investigated, such as molecular mixing fraction, efficiency Atwood number, turbulent mass-flux velocity and density self-correlation. Then, Reynolds stress and anisotropy are also investigated. Finally, the radial velocity, velocity divergence and enstrophy in the spherical and cylindrical turbulent mixing layers are studied using the method of conditional statistical analysis. Present numerical results show that the geometric effect has a great influence on the converging Richtmyer–Meshkov instability mixing layers.

“…Further, the soap film technique was recently utilised to generate an SF 6 gas layer with controlled perturbation and layer thickness. The heavy-fluid-layer evolution induced by a planar shock wave (Liang et al 2020;Liang & Luo 2021a,b) or a cylindrical converging shock wave (Ding et al 2019;Sun et al 2020) was explored. It was found that rarefaction waves and compression waves reverberating inside the heavy-fluid layer result in the first interface being more unstable and the second interface being more stable (Liang & Luo 2021a).…”

Section: Introductionmentioning

confidence: 99%

On shock-induced light-fluid-layer evolution

Luo

2021

Self Cite

Shock-induced light-fluid-layer evolution is firstly investigated experimentally and theoretically. Specifically, three quasi-one-dimensional helium gas layers with different layer thicknesses are generated to study the wave patterns and interface motions. Six quasi-two-dimensional helium gas layers with diverse layer thicknesses and amplitude combinations are created to explore the Richtmyer–Meshkov instability of a light-fluid layer. Due to the multiple reflected shocks reverberating inside a light-fluid layer, the speeds of the two interfaces gradually converge, and the layer thickness saturates eventually. A general one-dimensional theory is adopted to describe the two interfaces’ motions and the layer thickness variations. It is found that, for the first interface, the end time of its phase reversal determines the influence of the reflected shocks on it. However, the reverberated shocks indeed lead to the second interface being more unstable. When the two interfaces are initially in phase, and the initial fluid layer is very thin, the two interfaces’ spike heads collide and stabilise the two interfaces. Linear and nonlinear models are successfully adopted by considering the interface-coupling effect and the reverberated shocks to predict the two interfaces’ perturbation growths in all regimes. The interfacial instability of a light-fluid layer is quantitatively compared with that of a heavy-fluid layer. It is concluded that the kind of waves reverberating inside a fluid layer significantly affects the fluid-layer evolution.