Direct numerical simulation of a supersonic turbulent boundary layer subject to adverse pressure gradient induced by external successive compression waves

Wang, Xu; Wang, Zhenguo; Sun, Mao; Wang, Qiancheng; Hu, Zhiwei

doi:10.1063/1.5112040

Cited by 6 publications

(1 citation statement)

References 65 publications

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“…In supersonic flows, Wang et al. (2019 a , b ) observed similar and more evident large-scale motions under APG generated by either the small-angle concave walls or external successive compression waves. Wu, Liang & Zhao (2019) linked the large-scale motions to the energy spectra peak in the outer region, further validating the resemblance between compressible and ITBLs under APG.…”

Section: Transport Of Tkementioning

confidence: 90%

A spectral inspection for turbulence amplification in oblique shock wave/turbulent boundary layer interaction

Zhao

Tang

et al. 2022

J. Fluid Mech.

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Turbulence amplification and the large-scale coherent structures in shock wave/turbulent boundary layer interaction flows have been studied at length in previous research, while the direct association between these two flow features is still lacking. In the present study, the transport equation of turbulent kinetic energy spectra is derived and utilized to analyse the scale-by-scale energy budget across the interaction zone, enabling us to reveal the association between the genesis of the large-scale motions and the turbulence amplification. For the presently considered flow with incipient shock-induced separation, we identified in turbulent kinetic energy spectra distribution that the most energetic motions are converted from the near-wall small-scale motions to large-scale motions consisting of velocity streaks and cross-stream circulations as they go through the interaction zone. The amplification of streamwise velocity fluctuation is triggered first, resulting in the emergence of large-scale velocity streaks, which is attributed to the adverse pressure gradient, as indicated by the spectra of the production term. The energy carried by large-scale velocity streaks is transferred to other velocity components by the pressure-strain term, producing large-scale cross-stream circulations. When large-scale motions are convected downstream, their energy is transferred via turbulent cascade to smaller scales and dissipated by viscosity. The spanwise uniform fluctuations, reminiscent of the unsteadiness of the separation bubble, are contributed primarily by the inter-scale energy transfer from the finite spanwise scale motions.

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Section: Transport Of Tkementioning

confidence: 90%

A spectral inspection for turbulence amplification in oblique shock wave/turbulent boundary layer interaction

Zhao

Tang

et al. 2022

J. Fluid Mech.

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Effects of favorable pressure gradient on turbulence structures and statistics of a flat-plate supersonic turbulent boundary layer

Wang

Sun

et al. 2020

Physics of Fluids

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A Mach 2.9 flat-plate supersonic turbulent boundary layer subject to a moderate favorable pressure gradient (FPG) induced by external expansion waves is investigated through direct numerical simulation and compared with a zero pressure gradient (ZPG) boundary layer. It is found that under FPG, the logarithmic region in the van Driest transformed velocity profile is lifted above the log law, while the wake region deviates below its ZPG counterpart. The near-wall streaks are elongated in the streamwise direction with wider spanwise spacing, which leads to an attenuated meandering effect compared to the ZPG case. Although small-scale motions in the outer layer are evidently suppressed, they survive mostly in the inner layer. On the other hand, large-scale motions tend to correlate further with the lifted fluid from upstream due to bulk dilatation. However, their relative locations within the boundary layer remain unchanged. Different responses of turbulence structures in the inner and the outer layer to FPG show that this two-layer feature within the boundary layer is mainly associated with the bulk dilatation rather than the wall curvatures. The profiles of turbulent kinetic energy (TKE) and turbulent Mach number also show a two-layer behavior, where the reduction in turbulence in the outer layer is more prominent than in the inner. Positive convection occurs from the buffer to the outer layer according to the TKE budget analysis, which compensates the production and resists the decrease in the turbulence level.

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Response of a supersonic turbulent boundary layer to different streamwise adverse pressure gradients

Wen,

Wang,

Wei

et al. 2023

Physics of Fluids

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An adverse pressure gradient (APG) has an impact on the boundary layer, increasing the turbulent intensity of the layer. The mean and turbulent properties of the turbulent boundary layer on a flat plate with different APGs were investigated at Mach 2.7 in the present work utilizing the particle image velocimetry and nanoparticle-based planar laser scattering techniques. According to analysis, the changing trends of boundary layer parameters are different depending on whether the local mainstream velocity or freestream velocity of the wind tunnel is used to normalize. Using the former might make the enhanced effect of the rising APG more visible. With the rise in APG, the principal strain rate, turbulent fluctuation, Reynolds stress, and turbulence production in the boundary layer all increased, while the turbulent boundary layer's thickness dropped. Furthermore, the heightened upward ejection and downward sweep events caused the streamwise turbulence intensity to reach its outer peak under the influence of strong APG. The characteristics of the spanwise vortex in the boundary layer are investigated in conjunction with the probability density function analysis. The growing APG, which primarily promote negative vorticity, can strengthen the rotational strength of spanwise vortices, which are a component of hairpin vortices. As APG rises, the number of small-scale vortices in the boundary layer increases and the fractal dimension grows. The increase in small-scale vortices tends to induce strong transportation and promotes turbulence intensity. Further investigation reveals that the increased volume change caused by the enhanced compression effect with increasing APG exacerbated the vorticity.

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Direct numerical simulation of a supersonic turbulent boundary layer subject to adverse pressure gradient induced by external successive compression waves

Cited by 6 publications

References 65 publications

A spectral inspection for turbulence amplification in oblique shock wave/turbulent boundary layer interaction

A spectral inspection for turbulence amplification in oblique shock wave/turbulent boundary layer interaction

Effects of favorable pressure gradient on turbulence structures and statistics of a flat-plate supersonic turbulent boundary layer

Response of a supersonic turbulent boundary layer to different streamwise adverse pressure gradients

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