Structure and fluctuation characteristics of a compressible turbulent boundary layer behind a fan of rarefaction waves

Goldfeld, M. A.; Zinov'ev, V. N.; Lebiga, V. A.

doi:10.1007/bf01050847

Cited by 6 publications

(5 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Early researches mainly focused on the pressure gradient and the curvature effects of the expansion part of the configuration, including the increase of the boundary layer thickness, the reduction of turbulence intensity and heat transfer, the stabilization and the relaminarization of the boundary layer during the expansion process, etc. [5][6][7][8][9][10][11][12][13][14][15][16] A comprehensive review of researches on the supersonic flow passing an isolated expansion corner was presented by Knight et al 2 The suppression of turbulence during the expansion process 6,10,[12][13][14][15][16][17] is a significant characteristic in expansioncompression corner flows, and could cause the re-laminarization of the boundary layer when the flow undergoes a strong expansion process. 11,12,17 The reason for the turbulence being suppressed could be related to the combined effects of the favourable pressure gradient (FPG), the convex curvature of streamlines and the bulk dilatation (see the review of Knight et al 2 ).…”

Section: Figmentioning

confidence: 99%

“…Instead, the velocity develops into a wakelike profile immediately above the linear sub-layer, which is in agreement with the experimental observations in expansion corner flows. 12,13,17 This kind of change of the velocity profile can be explained by the suppression of turbulence structures that are responsible for the momentum transport in the log-layer during the interaction with the expansion wave. This observation is also in agreement with the two-layer model proposed by Gillis et al 20 , in which the anisotropic and productive turbulence evolves into isotropic 'debris' in the outer layer.…”

Section: B Separation Propertymentioning

confidence: 99%

“…The Reynolds stresses profiles along the 13 pre-defined sample lines are further studied. To better describe the Reynolds stresses above the slant ramp surface, the Reynolds stresses are decomposed according to the directions parallel and normal to the surface of the ramp respectively, which is expressed as 〈 ′′ ′′ 〉 = 〈(⃗ ′′ ⋅ ⃗⃗⃗⃗ )(⃗ ′′ ⋅ ⃗⃗⃗⃗ )〉 〈 ′′ ′′ 〉 = 〈(⃗ ′′ ⋅ ⃗⃗⃗⃗ )(⃗ ′′ ⋅ ⃗⃗⃗⃗ )〉 〈 ′′ ′′ 〉 = 〈(⃗ ′′ ⋅ ⃗⃗⃗⃗ )(⃗ ′′ ⋅ ⃗⃗⃗⃗ )〉 , (13) in which ⃗ ′′ is the fluctuation velocity vector, ⃗⃗⃗⃗ and ⃗⃗⃗⃗ are the unit vector parallel and normal to the surface of the wall,…”

Section: Reynolds Stressesmentioning

confidence: 99%

See 2 more Smart Citations

Direct numerical simulation of supersonic turbulent flows around a tandem expansion-compression corner

et al. 2015

View full text Add to dashboard Cite

The M=2.9 supersonic turbulent flows over a tandem expansion-compression corner configuration with a sharp deflection angle of 25° at three Reynolds numbers Re = 20000, 40000 and 80000 were studied by using direct numerical simulation (DNS). The flow statistics were validated against available experimental measurements and other numerical predictions. The flow structures and turbulence statistics were detailed visualized and analysed for the Re = 40000 case, especially in the interaction region where flow separation and reattachment occurred. It was found that during the expansion process the boundary layer exhibited a characteristic two-layer structure also discovered in previous experimental studies, and the turbulence evolved differently within these two layers. In the outer layer the turbulence was consistently suppressed along the ramp to a large extent, while in the inner layer it was suppressed only in a small region around the expansion corner, and the near-wall quasi-streamwise vortices were well preserved. Flow patterns near the reattachment line have shown the existence of the Görtler-type vortices, which would largely amplify turbulence fluctuations in the near-wall region, thus promoting the regeneration of wall turbulence that in turn contributed to the redevelopment of a downstream turbulent boundary layer. The Reynolds number effects and the characteristics of coherent structures were also discussed. With the increase of the Reynolds number, the separation bubble size decreased, but the pattern and the characteristic size of wall streamlines near the reattachment line were preserved.

show abstract

Section: Figmentioning

confidence: 99%

Section: B Separation Propertymentioning

confidence: 99%

Section: Reynolds Stressesmentioning

confidence: 99%

See 1 more Smart Citation

Direct numerical simulation of supersonic turbulent flows around a tandem expansion-compression corner

et al. 2015

View full text Add to dashboard Cite

show abstract

“…The problem of relaminarization has been studied from the last mid-century. An investigation of subsonic turbulent flows in the presence of a large negative pressure gradient showed the possibility of complete boundary layer relaminarization [2][3][4][5], which is connected with the curved nature of streamlines and favorable longitudinal and normal pressure gradients which lead to a rapid diminishing of the turbulent fluctuation scale in the flow acceleration region [6]. The longitudinal gradient of the static pressure and the freestream Reynolds number were noted as the basic flow parameters influencing the generation and development of the relaminarization process.…”

Section: Nomenclaturementioning

confidence: 99%

Numerical Simulation of Disturbance Evolution in the Supersonic Boundary Layer over an Expansion Corner

Chuvakhov

Егоров

2021

Fluid Dyn

View full text Add to dashboard Cite

Abstract— The linear and nonlinear stages of disturbance development in the supersonic boundary layer over a 10° expansion corner is investigated numerically within the framework of Navier—Stokes equations for Mach number 3. The effect of sudden flow expansion on the disturbance evolution is analyzed. The flow stabilization effect observable in the aerodynamic experiment is also discussed.

show abstract

“…Intuitively, we can anticipate line widths will decrease above the southern discontinuity in Figure 13 for two reasons. First, the production of turbulence being suppressed following the passing of a rarefaction wave (Gol'dfel'd et al 1987), we expect a monotonic dissipation of the vorticity as the material travels away from the southern discontinuity. Secondly, the fact that the rarefied material converges straight at the shell opening diminishes the number of radial velocity gradients along the line of sight in the zone of rarefaction.…”

Section: Analogy: W4-north As a Pierced Metal Containermentioning

confidence: 99%

ON THE DYNAMICAL EVOLUTION OF H II REGIONS: AN INVESTIGATION OF THE IONIZED COMPONENT OF W4, A GALACTIC CHIMNEY CANDIDATE. I. KINEMATICS AND DYNAMICS IN THE LATITUDE RANGE 0° ⩽b⩽ 3°

Lagrois

Joncas

2009

ApJ

View full text Add to dashboard Cite

In the second of this two-paper series, we present results associated with an Hα investigation, obtained using the Fabry-Perot interferometer FaNTOmM, of the tenuous ionized material found embedded in the northern portion of W4. W4 is a promising candidate for a galactic chimney, likely connected with the galactic corona, and presents evidence of shell fragmentation. We present the quantitative method for identifying shell breakout that allows us to characterize the giant H i supershell/H ii region W4 as enclosing a galactic chimney in formation. On a range of approximately 125 pc, two "south-to-north" radial velocity gradients are detected, ∇ v = (−)0.17 km s −1 pc −1 (3. • 5 b < 6. • 3) and ∇ v = (−)3.13 km s −1 pc −1 (6. • 3 b 6. • 5). This leads to radial velocities, slightly above the vicinity of the shell's polar cap, of −70 km s −1 , blueshifted by nearly 25 km s −1 with respect to the H i supershell. The kinematic behavior is in agreement with a rarefaction scenario if the W4 superbubble presents a tilt toward the observer. This angle of inclination is estimated between 9 • and 27 • with respect to the plane of the sky. A line-narrowing gradient is correlated with the radial velocity gradient. The large-scale trends in radial velocities and line widths correspond to highly accelerated, well-parallelized outflows of vented ionized material. This kinematic signature is expected from the chimney model. The dynamical age of the W4 chimney is estimated at 4.1 Myr and constraints shell instabilities to have developed at latitudes lower than the blowout threshold height. Our work contributes to the evidence that the star cluster IC 1805 partially sustains the low-galactic corona above the Perseus arm.

show abstract

Structure and fluctuation characteristics of a compressible turbulent boundary layer behind a fan of rarefaction waves

Cited by 6 publications

References 3 publications

Direct numerical simulation of supersonic turbulent flows around a tandem expansion-compression corner

Direct numerical simulation of supersonic turbulent flows around a tandem expansion-compression corner

Numerical Simulation of Disturbance Evolution in the Supersonic Boundary Layer over an Expansion Corner

ON THE DYNAMICAL EVOLUTION OF H II REGIONS: AN INVESTIGATION OF THE IONIZED COMPONENT OF W4, A GALACTIC CHIMNEY CANDIDATE. I. KINEMATICS AND DYNAMICS IN THE LATITUDE RANGE 0° ⩽b⩽ 3°

Contact Info

Product

Resources

About