On the compressibility effects in mixing layers

Khlifi, H.; Tong, Lili

doi:10.2298/tsci130619059k

Cited by 5 publications

(2 citation statements)

References 19 publications

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“…Its contribution to the turbulent production in the outer region manifests no trend to decrease. The pressure-strain term of Reynolds stress components, defined as 17(d), further suggesting the maintenance of the axisymmetric expansion state of Reynolds stress in the dynamical sense (Foysi, Sarkar & Friedrich 2004;Khlifi & Lili 2016;Li et al 2022).…”

Section: Transport Of Tkementioning

confidence: 99%

Post-shock turbulence recovery in oblique-shock/turbulent boundary layer interaction flows

Dong

Liu

et al. 2023

J. Fluid Mech.

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The oblique shock impinging on the supersonic turbulent boundary layer leads to a mixing layer and the emergence of large-scale coherent structures within the interaction zone which leave significant velocity defect and turbulence amplification downstream. In the present study, we investigate the turbulence recovery in the post-shock region by exploiting direct numerical simulation data of the oblique-shock/turbulent boundary layer interaction flow at the incoming Mach number of $2.28$ and the shock angle of $33.2^\circ$ , with special attention paid to the contribution of the mixing layer and large-scale structures to flow dynamics. For that purpose, we propose to split the mean velocity, Reynolds stresses and spanwise spectra into a canonical portion that is constructed according to the statistics of canonical turbulent boundary layers, and a mixing-layer-induced portion. We found that the hidden mixing layer grows with the boundary layer thickness and that the induced mean shear and Reynolds stresses decay at different rates. The mean velocity recovers to the canonical profiles at a distance of 13 boundary layer thicknesses downstream where the mixing-layer-induced mean shear ceases to have strong impacts. The recovery of Reynolds stresses requires 10 boundary layer thicknesses in the near-wall region but a much longer streamwise extent in the outer region due to the slow decay of large-scale motions. These large-scale motions superpose on the near-wall turbulence, intensifying the turbulent fluctuations, yet having a trivial impact on the skin friction, for the contribution of the mixing-layer-induced mean shear and Reynolds shear stress are balanced by the advection term. We further establish a simple physical model capable of approximately predicting the streamwise evolution of mixing-layer-induced mean shear and turbulent kinetic energy. This model suggests that the complete recovery of turbulence in the outer region requires a streamwise extent of approximately 50 boundary layer thicknesses.

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Section: Transport Of Tkementioning

confidence: 99%

Post-shock turbulence recovery in oblique-shock/turbulent boundary layer interaction flows

Dong

Liu

et al. 2023

J. Fluid Mech.

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“…With respect to the incompressible case, many compressible models have been developed for the pressure-strain correlation. Hereafter, most of all these models are generated from a simple extension of its incompressible counter-part as in [14][15][16][17], in general, they perform well in the simulation of important turbulent flows evolving with moderate compressibility.…”

Section: Governing Equationsmentioning

confidence: 99%

A compressibility corrections of the pressure strain linear part models

Khlifi¹

2018

THERM SCI

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The main focus of this paper is the analysis of the compressibility effects and the validation of some recent Reynolds stress models for computing compressible turbulent flows. The pressure strain correlation is one of the several terms appearing in the Reynolds stress equation which directly reflect the compressibility effects on the turbulence. For this reason, a special attention is paid to the modeling of this term in order to account for compressibility effects at high-speed. The models developed by Speziale Sarkar and Gatski (SSG) and Fu, Launder and Tselepidakis (FLT) for the pressure strain correlation are examined to be extended to compressible turbulent flows. A compressibility corrections of these models using the turbulent Mach number are proposed. The calculations have been performed for the compressible homogeneous shear flow and the turbulent plate mixing-layers. The comparison of the proposed compressibility modifications of the SSG and FLT models with its universal version shows some important ameliorations in results for the majority characteristic parameter of the structural compressibility effects. It's found that the predicted results from the modified SSG and FLT models are in reasonable agreement with the accepted data.

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