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Multimedia files – 9/13 Streak instability in adverse pressure gradient boundary layer

Multimedia files – 9/13 Streak instability in adverse pressure gradient boundary layer. Contents: 1. Test model 2. Basic flow 3. V aricose instability of the streak, ZPG 4. V aricose instability of the streak, APG 5. Related publications. 1. Test model.

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Multimedia files – 9/13 Streak instability in adverse pressure gradient boundary layer

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  1. 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

  2. 1. Test model Sketch of the experimental model (see page of notes)

  3. 2. Basic flow Characteristicsof the undisturbed boundary layer at zero and adverse pressure gradients: velocity variationalong the external boundary layer edge (a), variation of the boundary layermomentumthickness (b), and the velocity profiles (c);hot-wire data (symbols), theoreticalapproximations (lines)

  4. 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 velocityU– UB and rms velocity u' (shading);negative contours are shown by blue lines; depictedred arc has diameter of 2 mm;contour step is 0.2DU0.5for 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)

  5. 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

  6. 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)

  7. 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 ofuave = U + u'

  8. 4. Varicose instability of the streak, APG (I) (a) (b) Varicose instability of the streaky structure, APG. Contours of mean disturbance velocityU– UB and rms velocity u' (shading);negative contours are shown by blue lines; depictedred arc has diameter of 2 mm;contour step is 0.2DU0.5for 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)

  9. 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 ofutot = uave – UB

  10. 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)

  11. 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 ofuave = U + u' (see page of notes)

  12. 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.

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