Multimedia files – 9/13
Streak instability in adverse
pressure gradient boundary layer
Contents:
1. Test model
2. Basic flow
3. Varicose instability of the streak, ZPG
4. Varicose instability of the streak, APG
5. Related publications
1. Test model
Sketch of the experimental model
(see page of notes)
2. Basic flow
Characteristics of the undisturbed boundary layer at zero and adverse pressure gradients:
velocity variation along the external boundary layer edge (a), variation of the boundary
layer momentum thickness (b), and the velocity profiles (c); hot-wire data (symbols),
theoretical approximations (lines)
3. Varicose instability of the streak, ZPG (I)
(a)
(x-x1 )/1= 173
(b)
(x-x1 )/1= 119
(x-x1 )/1= 79
Varicose instability of the streaky structure, ZPG. Contours of mean disturbance velocity U – UB
and rms velocity u' (shading); negative contours are shown by blue lines; depicted red arc has
diameter of 2 mm; contour step is 0.2DU0.5 for U - UB, and 0.02Ue for u' (a). Instantaneous spatial
distribution of utot, iso - levels are +3.5% of Ue(grey) and –3.5% of Ue(blue) (b)
(see page of notes)
3. Varicose instability of the streak, ZPG (II)
Click to play
A video clip by Chernoray V.G., Kozlov V.V., Löfdahl L., Litvinenko Yu.A. (2004)
illustrating the behavior of utot = uave – UB
3. Varicose instability of the streak, ZPG (III)
(a)
(b)
(c)
Instantaneous distributions of fluctuation velocity as isosurface levels at ± 2 % (a),
± 1 % (b), and ± 0.5 % (c); negative levels are coloured dark grey
(see page of notes)
3. Varicose instability of the streak, ZPG (IV)
Click to play
A video clip by Chernoray V.G., Kozlov V.V., Löfdahl L., Litvinenko Yu.A.
(2004) illustrating the behavior of uave = U + u'
4. Varicose instability of the streak, APG (I)
(a)
(b)
Varicose instability of the streaky structure, APG. Contours of mean disturbance velocity U – UB
and rms velocity u' (shading); negative contours are shown by blue lines; depicted red arc has
diameter of 2 mm; contour step is 0.2DU0.5 for U - UB, and 0.02Ue for u' (a). Instantaneous spatial
distribution of utot, iso - levels are +2.0% of Ue(grey) and –2.0% of Ue(blue) (b)
(see page of notes)
4. Varicose instability of the streak, APG (II)
Click to play
A video clip by Chernoray V.G., Kozlov V.V., Löfdahl L., Litvinenko Yu.A. (2004)
illustrating the behavior of utot = uave – UB
4. Varicose instability of the streak, APG (III)
(a)
(b)
(c)
Instantaneous distributions of fluctuation velocity as isosurface levels at ± 7 % (a),
± 3 % (b), and ± 1 % (c); negative levels are coloured dark grey
(see page of notes)
4. Varicose instability of the streak, APG (IV)
Click to play
A video clip by Chernoray V.G., Kozlov V.V., Löfdahl L., Litvinenko Yu.A. (2004)
illustrating the behavior of uave = U + u'
(see page of notes)
5. Related publications
Andersson, P., Brandt, L., Bottaro, A., Henningson D.S. (2001) On the breakdown of boundary layer
streaks. J. Fluid Mech., 428, 29-60.
Asai M., Minagawa M., Nishioka M. (2002) The stability and breakdown of near-wall low-speed streak.
J. Fluid Mech., 455, 289-314.
Chernoray V.G., Kozlov V.V., Lee, I., Chun, H.H. (2007) Visualization of varicose instability of streaks
in a boundary layer. J. Visualization, 10(2), 217-225.
Chernoray V.G., Kozlov V.V., Löfdahl L., Chun, H.H. (2006) Visualization of sinusoidal and varicose
instabilities of streaks in a boundary layer. J. Visualization, 9(4), 437-444.
Kozlov V.V., Chernoray V.G., Litvinenko Yu.A., Löfdahl L. (2004) Breakdown of a streak via
development of varicose secondary mode on the staight wing with pressure gradient. In Proc. of the
Tenth European Turbulence Conference, 29 June-2 July, 2004, Norway,Trondheim, 77-80.
Litvinenko Yu.A., Chernorai V.G., Kozlov V.V., Loefdahl L., Grek G.R., Chun H.H. (2005) Adverse
pressure gradient effect on nonlinear varicose instability of a streaky structure in an unswept wing
boundary layer. Phys. Fluids, 17, 118106(1)-118106(3).
Skote M., Haritonidis J.H., Henningson D.S. (2002) Varicose instabilities in turbulent boundary layers.
Phys. Fluids, 4(7), 2309-2323.