Preponderance of hairpin vortices detected from very-large-scale, direct numerical simulations of three flat-plate boundary layers

2011 ◽  
Author(s):  
Xiaohua Wu ◽  
Parviz Moin
Keyword(s):  
Numerical Simulations ◽  
Flat Plate ◽  
Boundary Layers ◽  
Large Scale ◽  
Plate Boundary ◽  
Direct Numerical Simulations ◽  
Hairpin Vortices

scholarly journals Oblique route to turbulence

2011 ◽  
Vol 674 ◽  
pp. 1-4
Author(s):  
MUJEEB R. MALIK
Keyword(s):  
Boundary Layer ◽  
Numerical Simulations ◽  
Flat Plate ◽  
Boundary Layers ◽  
Plate Boundary ◽  
Direct Numerical Simulations ◽  
Two Dimensional ◽  
Mach 3 ◽  
Transition Scenario ◽  
Flat Plate Boundary Layer

Direct numerical simulations have been performed by Mayer, Von Terzi & Fasel (J. Fluid Mech., this issue, vol. 674, 2011, pp. 5–42) to demonstrate that oblique-mode breakdown leads to fully turbulent flow for a Mach 3 flat-plate boundary layer. Since very low level of initial disturbances is required for this transition scenario, oblique-mode breakdown is the most potent mechanism for transition in two-dimensional supersonic boundary layers in low-disturbance environments relevant to flight.

Direct numerical simulations of roughness-induced transition in supersonic boundary layers

2012 ◽  
Vol 693 ◽  
pp. 28-56 ◽  
Author(s):  
Suman Muppidi ◽  
Krishnan Mahesh
Keyword(s):  
Numerical Simulations ◽  
Shear Layer ◽  
Boundary Layers ◽  
Plate Boundary ◽  
Direct Numerical Simulations ◽  
Transition To Turbulence ◽  
Streamwise Vortices ◽  
Mean Flow ◽  
The Mean ◽  
Near Wall

AbstractDirect numerical simulations are used to study the laminar to turbulent transition of a Mach 2.9 supersonic flat plate boundary layer flow due to distributed surface roughness. Roughness causes the near-wall fluid to slow down and generates a strong shear layer over the roughness elements. Examination of the mean wall pressure indicates that the roughness surface exerts an upward impulse on the fluid, generating counter-rotating pairs of streamwise vortices underneath the shear layer. These vortices transport near-wall low-momentum fluid away from the wall. Along the roughness region, the vortices grow stronger, longer and closer to each other, and result in periodic shedding. The vortices rise towards the shear layer as they advect downstream, and the resulting interaction causes the shear layer to break up, followed quickly by a transition to turbulence. The mean flow in the turbulent region shows a good agreement with available data for fully developed turbulent boundary layers. Simulations under varying conditions show that, where the shear is not as strong and the streamwise vortices are not as coherent, the flow remains laminar.

A study in transitional flat plate boundary layers: measurement and visualization

2000 ◽  
Vol 28 (3) ◽  
pp. 243-251 ◽  
Author(s):  
C. B. Lee ◽  
Z. X. Hong ◽  
Y. S. Kachanov ◽  
V. I. Borodulin ◽  
V. V. Gaponenko
Keyword(s):  
Flat Plate ◽  
Boundary Layers ◽  
Plate Boundary
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