Evolution of scalar and velocity dynamics in planar shock-turbulence interaction

Boukharfane, Radouan; Bouali, Zakaria; Mura, Arnaud

doi:10.1007/s00193-017-0798-5

Cited by 29 publications

(34 citation statements)

References 68 publications

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“…For Reynolds stresses, large-scale turbulent variables, the multi-fluid flow reaches a quasi-isotropic state immediately after the shock wave (b 11 ≈ 0.0), while single-fluid turbulence exhibits a tendency towards an axisymmetric state. This is in good agreement with Boukharfane et al (2018). Evidently, the variable density effects on the post-shock turbulence appear differently at small and large scales.…”

Section: Evolution Of Turbulence State Downstream Of the Shocksupporting

confidence: 88%

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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: Evolution Of Turbulence State Downstream Of the Shocksupporting

confidence: 88%

“…2013; Boukharfane et al. 2018). More importantly, the vortex tubes also become aligned with the density iso-surfaces, meaning that the vorticity becomes perpendicular to the density gradient.…”

Section: Resultsmentioning

confidence: 99%

Density effects on post-shock turbulence structure and dynamics

2019

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“…In figure 4 we show streamwise profiles of the dilatational term A, the turbulent diffusion term C and the scalar dissipation rate term E. The latter dominates, in agreement with Tian et al (2017), while all three terms increase across the shock. Tian et al 2017did not perform a parametric study of different terms in (3.1), while Boukharfane et al (2018) only studied the effects of M (for 1.7, 2.0 and 2.3) on the scalar dissipation term. Dilatational and turbulent diffusion terms reach about ten percent of the scalar dissipation rate term downstream of the shock, in contrast to the results of Tian et al 2017, who found these two terms to be negligible for the mixing of passive scalars, but not for multi-fluid mixing.…”

Section: Scalar Variance Budgetsmentioning

confidence: 99%

Parametric numerical study of passive scalar mixing in shock turbulence interaction

2020

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“…Intensity and orientation of both strain and vorticity may be altered, which eventually plays on the growth rate and alignment of scalar gradients. Through the velocity gradient, mass density gradients may thus influence the mixing process, a phenomenon addressed in compressible turbulence [1,2] and in turbulent flames [3][4][5].…”

Section: Introductionmentioning

confidence: 99%