Linear and nonlinear development of instabilities in shear layers

2001 ◽  
Author(s):  
E. Longatte ◽  
P. Lafon ◽  
S. Candel
Keyword(s):  
Shear Layers ◽  
Nonlinear Development ◽  
Linear And Nonlinear

Linear and nonlinear development of m=0 instability in a diffuse Bennett Z-pinch equilibrium with sheared axial flow

2010 ◽  
Vol 17 (7) ◽  
pp. 072107 ◽  
Author(s):  
I. Paraschiv ◽  
B. S. Bauer ◽  
I. R. Lindemuth ◽  
V. Makhin
Keyword(s):  
Axial Flow ◽  
Nonlinear Development ◽  
Linear And Nonlinear ◽  
Z Pinch

Linear and Nonlinear Development of the m = 0 Instability in Z-Pinch Equilibria with Axial Sheared Flows

2008 ◽  
Vol 28 (2) ◽  
pp. 195-199
Author(s):  
Ioana Paraschiv ◽  
Bruno S. Bauer ◽  
Irvin R. Lindemuth ◽  
Volodymyr Makhin
Keyword(s):  
Nonlinear Development ◽  
Sheared Flows ◽  
Linear And Nonlinear ◽  
Z Pinch

On the linear and nonlinear development of Görtler vortices

2008 ◽  
Vol 20 (9) ◽  
pp. 094103 ◽  
Author(s):  
Tandiono ◽  
S. H. Winoto ◽  
D. A. Shah
Keyword(s):  
Nonlinear Development ◽  
Görtler Vortices ◽  
Linear And Nonlinear ◽  
Gortler Vortices

Linear and Nonlinear Development of the M=0 Instability in z-pinch Equilibria with Axial Sheared Flows

2007 ◽  
Author(s):  
Ioana Paraschiv ◽  
Bruno S. Bauer ◽  
Irvin R. Lindemuth ◽  
Vladimir I. Sotnikov ◽  
Vlad Makhin ◽  
...  
Keyword(s):  
Nonlinear Development ◽  
Sheared Flows ◽  
Linear And Nonlinear ◽  
Z Pinch

Linear and nonlinear processes in two-dimensional mixing layer dynamics and sound radiation

2009 ◽  
Vol 625 ◽  
pp. 321-351 ◽  
Author(s):  
LAWRENCE C. CHEUNG ◽  
SANJIVA K. LELE
Keyword(s):  
Near Field ◽  
Shear Layers ◽  
Wave Radiation ◽  
Instability Wave ◽  
Sound Generation ◽  
Instability Waves ◽  
Vortical Structures ◽  
Vortex Pairing ◽  
Linear And Nonlinear ◽  
Field Sound

In this study, we consider the effects of linear and nonlinear instability waves on the near-field dynamics and aeroacoustics of two-dimensional laminar compressible mixing layers. Through a combination of direct computations, linear and nonlinear stability calculations, we demonstrate the significant role of nonlinear mechanisms in accurately describing the behaviour of instability waves. In turn, these processes have a major impact on sound generation mechanisms such as Mach wave radiation and vortex pairing sound. Our simulations show that the mean flow correction, which is required in order to accurately describe the dynamics of large-scale vortical structures, is intrinsically tied to the nonlinear modal interactions and accurate prediction of saturation amplitudes of instability waves. In addition, nonlinear interactions are largely responsible for the excitation and development of higher harmonics in the flow which contribute to the acoustic radiation. Two flow regimes are considered: In supersonic shear layers, where the far-field sound is determined by the instability wave solution at sufficiently high Mach numbers, it is shown that these nonlinear effects directly impact the Mach wave radiation. In subsonic shear layers, correctly capturing the near-field vortical structures and the interactions of the subharmonic and fundamental modes become critical due to the vortex pairing sound generation process. In this regime, a method is proposed to combine the instability wave solution with the Lilley–Goldstein acoustic analogy in order to predict far-field sound.

Breakdown mechanisms and heat transfer overshoot in hypersonic zero pressure gradient boundary layers

2013 ◽  
Vol 730 ◽  
pp. 491-532 ◽  
Author(s):  
Kenneth J. Franko ◽  
Sanjiva K. Lele
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Plate Boundary ◽  
Transitional Region ◽  
Mean Flow ◽  
Fundamental Resonance ◽  
Nonlinear Development ◽  
Second Mode ◽  
Linear And Nonlinear ◽  
Streamwise Streaks

AbstractA laminar Mach 6 flat plate boundary layer is perturbed using three different types of disturbances introduced through blowing and suction. The linear and nonlinear development and eventual breakdown to turbulence are investigated using direct numerical simulation. The three different transition mechanisms compared are first mode oblique breakdown, second mode oblique breakdown and second mode fundamental resonance. The focus of the present work is to compare the nonlinear development and breakdown to turbulence for the different transition mechanisms and explain the heat transfer overshoot observed in experiments. First mode oblique breakdown leads to the shortest transition length and a clear peak in wall heat transfer in the transitional region. For all three transition mechanisms, the development of streamwise streaks precedes the breakdown to fully turbulent flow. The modal linear and nonlinear development are analysed including the breakdown of the streaks. The effect of wall cooling is investigated for second mode fundamental resonance and no qualitative differences in the nonlinear processes are observed. Finally, the development towards fully turbulent flow including mean flow, turbulent spectra, and turbulent fluctuations is shown and the first mode oblique breakdown simulation shows the furthest development towards a fully turbulent flow.

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