Shock Propagation in Media with Non-uniform Density

Livescu, Daniel; Tian, Yifeng; Jaberi, Farhad

doi:10.1007/978-3-319-91020-8_141

Cited by 5 publications

(1 citation statement)

References 11 publications

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“…The quantitative difference is hypothesized to be related to the higher shock strength variation in the multi-fluid case. It was observed in our previous studies (Tian, Jaberi & Livescu 2019) that the local shock strength is positively correlated with the pre-shock density. With a stronger shock, the two-dimensionalization effect on the post-shock turbulence should also appear stronger in the high-density regions (Livescu & Ryu 2016).…”

Section: Resultsmentioning

confidence: 65%

Density effects on post-shock turbulence structure and dynamics

2019

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Turbulence structure resulting from multi-fluid or multi-species, variable-density isotropic turbulence interaction with a Mach 2 shock is studied using turbulence-resolving shock-capturing simulations and Eulerian (grid) and Lagrangian (particle) methods. The complex roles density play in the modification of turbulence by the shock wave are identified. Statistical analyses of the velocity gradient tensor (VGT) show that the density variations significantly change the turbulence structure and flow topology. Specifically, a stronger symmetrization of the joint probability density function (PDF) of second and third invariants of the anisotropic velocity gradient tensor, PDF(Q * , R * ), as well as the PDF of the vortex stretching contribution to the enstrophy equation, are observed in the multi-species case. Furthermore, subsequent to the interaction with the shock, turbulent statistics also acquire a differential distribution in regions having different densities. This results in a nearly symmetrical PDF(Q * , R * ) in heavy fluid regions, while the light fluid regions retain the characteristic tear-drop shape. To understand this behavior and the return to "standard" turbulence structure as the flow evolves away from the shock, Lagrangian dynamics of the VGT and its invariants are studied by considering particle residence times and conditional particle variables in different flow regions. The pressure Hessian contributions to the VGT invariants transport equations are shown to be not only affected by the shock wave, but also by the density in the multi-fluid case, making them critically important to the flow dynamics and turbulence structure. arXiv:1908.05327v1 [physics.flu-dyn]

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Section: Resultsmentioning

confidence: 65%

Density effects on post-shock turbulence structure and dynamics

2019

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Shock-Turbulence Interaction in Variable Density Flows

Tian

Jaberi

Livescu

2020

Modeling and Simulation of Turbulent Mixing and Reaction

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Turbulence with Large Thermal and Compositional Density Variations

Livescu

2020

Annu. Rev. Fluid Mech.

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Density variations in fluid flows can arise due to acoustic or thermal fluctuations, compositional changes during mixing of fluids with different molar masses, or phase inhomogeneities. In particular, thermal and compositional (with miscible fluids) density variations have many similarities, such as in how the flow interacts with a shock wave. Two limiting cases have been of particular interest: ( a) the single-fluid non-Oberbeck–Boussinesq low–Mach number approximation for flows with temperature variations, which describes vertical convection, and ( b) the incompressible limit of mixing between miscible fluids with different molar masses, which describes the Rayleigh–Taylor instability. The equations describing these cases are remarkably similar, with some differences in the molecular transport terms. In all cases, strong inertial effects lead to significant asymmetries of mixing, turbulence, and the shape of mixing layers. In addition, density variations require special attention in turbulence models to avoid viscous contamination of the large scales.

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Shock Propagation in Media with Non-uniform Density

Cited by 5 publications

References 11 publications

Density effects on post-shock turbulence structure and dynamics

Density effects on post-shock turbulence structure and dynamics

Shock-Turbulence Interaction in Variable Density Flows

Turbulence with Large Thermal and Compositional Density Variations

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