Effect of pressure gradient in the connection region on the stability of the edge pedestal

2020 ◽  
Vol 60 (7) ◽  
pp. 076022
Author(s):  
S.K. Kim ◽  
S. Saarelma ◽  
Y.-S. Na ◽  
O. Kwon
Keyword(s):  
Pressure Gradient ◽  
Effect Of Pressure ◽  
The Stability

Effect of pressure gradient on the stability of compressible boundary layers

AIAA Journal ◽  
1992 ◽  
Vol 30 (9) ◽  
pp. 2204-2211 ◽  
Author(s):  
Y. H. Zurigat ◽  
A. H. Nayfeh ◽  
J. A. Masad
Keyword(s):  
Pressure Gradient ◽  
Boundary Layers ◽  
Effect Of Pressure ◽  
Compressible Boundary Layers ◽  
The Stability

Transition of streamwise streaks in zero-pressure-gradient boundary layers

2002 ◽  
Vol 472 ◽  
pp. 229-261 ◽  
Author(s):  
LUCA BRANDT ◽  
DAN S. HENNINGSON
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
High Speed ◽  
Plate Boundary ◽  
Transition Process ◽  
Free Stream Turbulence ◽  
Tollmien Schlichting ◽  
Streamwise Streaks ◽  
The Stability ◽  
Optimal Disturbances

A transition scenario initiated by streamwise low- and high-speed streaks in a flat-plate boundary layer is studied. In many shear flows, the perturbations that show the highest potential for transient energy amplification consist of streamwise-aligned vortices. Due to the lift-up mechanism these optimal disturbances lead to elongated streamwise streaks downstream, with significant spanwise modulation. In a previous investigation (Andersson et al. 2001), the stability of these streaks in a zero-pressure-gradient boundary layer was studied by means of Floquet theory and numerical simulations. The sinuous instability mode was found to be the most dangerous disturbance. We present here the first simulation of the breakdown to turbulence originating from the sinuous instability of streamwise streaks. The main structures observed during the transition process consist of elongated quasi-streamwise vortices located on the flanks of the low-speed streak. Vortices of alternating sign are overlapping in the streamwise direction in a staggered pattern. The present scenario is compared with transition initiated by Tollmien–Schlichting waves and their secondary instability and by-pass transition initiated by a pair of oblique waves. The relevance of this scenario to transition induced by free-stream turbulence is also discussed.

Modeling of External Pressure Gradient Influence on the Stability of Disturbances in the Boundary Layers of Compressed Gas

2013 ◽  
Vol 8 (4) ◽  
pp. 64-75
Author(s):  
Sergey Gaponov ◽  
Natalya Terekhova
Keyword(s):  
Mach Number ◽  
Pressure Gradient ◽  
Boundary Layers ◽  
Leading Edge ◽  
External Pressure ◽  
Transition To Turbulence ◽  
Compressed Gas ◽  
High Mach ◽  
The Stability ◽  
Very High

This work continues the research on modeling of passive methods of management of flow regimes in the boundary layers of compressed gas. Authors consider the influence of pressure gradient on the evolution of perturbations of different nature. For low Mach number M = 2 increase in pressure contributes to an earlier transition of laminar to turbulent flow, and, on the contrary, drop in the pressure leads to a prolongation of the transition to turbulence. For high Mach number M = 5.35 found that the acoustic disturbances exhibit a very high dependence on the sign and magnitude of the external gradient, with a favorable gradient of the critical Reynolds number becomes smaller than the vortex disturbances, and at worst – boundary layer is destabilized directly on the leading edge

On the stability of viscous flow in a curved channel

1958 ◽  
Vol 244 (1237) ◽  
pp. 186-198 ◽  
Keyword(s):  
Approximate Solution ◽  
Pressure Gradient ◽  
Viscous Flow ◽  
Close Agreement ◽  
Curved Channel ◽  
A Value ◽  
Concentric Cylinders ◽  
The Stability ◽  
Pattern Of Motion

In this paper the stability of viscous flow between two concentric cylinders due to a pressure gradient acting round the cylinders is considered when the spacing between the cylinders is small compared with their radii. Two methods of approximate solution are described, both of which show that instability first sets in when the parameter R √( d / R 1 ) attains a value of about 36 in close agreement with earlier results of Dean (1928). The pattern of motion which then sets in is of the familar cellular type but with a marked asymmetry.

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