a research about the different regimes of fluid flow past bluff bodies.

1. Research of the flow past bluff body
Mohamed Kabl
Supervised by
doc. Ing. Tomáš Vít, Ph.D.
Ing. Petra Dančová, Ph.D. 31/5/2016

2. Outline
• Introduction
• Experimental technique
• Results and discussion
• Conclusion
• Future work

3. Introduction

4. Introduction
Hydrodynamic and Aerodynamic bodies
Streamlined body Bluff body
A body for which the stream-wise dimension is
much larger than the cross-flow dimension is
often considered to be aerodynamic.
A body which its dimension in the direction of
the incoming flow is comparable to its dimension
in a direction normal to the flow.

5. Experimental
procedures
Components

6. Circular cylinder
Towing tank
Electrolysis hydrogen perciption
Laser sheet L = 300 mm D = 6.6 mm
λ = 45.3
500 X 110 X 110 cm3Tin Ion Visualization method
Width =1 mm
Frequency = 200 Hz

7. Experimental
procedures
Two different configurations
1. Span wise configuration.
2. Stream wise configuration.

8. Span wise configuration

9. Streamwise configuration

10. Results and discusion Re < 47 Laminar flow regime
47 < Re < 90 Onset of von Kármán vortex regime
90 < Re < 180 Pure von Kármán vortex shedding

11. Laminar flow regime Re = 30
Two attached vortex to the cylinder
Absence of von Kármán vortex
Small cyclic length
Large separation angle ≃ 135
Stagnation angle ≃ 0

12. Onset of von Kármán vortex Regime Re = 50
Low frequency vortex shedding
Small vortex size
Longer cyclic length
Large separation angle ≃ 125
Stagnation angle ≃ 0
Parallel vortex shedding past cylinder

13. Transition between the onset of von Kármán vortex
Regime and the pure vortex shedding regime Re = 90
Reasonable vortex shedding frequency
Intermediate vortex size
Longer cyclic length
Separation angle ≃ 110
Stagnation angle ≃ 0
Parallel vortex shedding past cylinder
with periodic oblique shedding

14. Pure vortex shedding regime Re = 130
High vortex shedding frequency
Large vortex size
Long cyclic length
Small wave length
Unparallel vortex shedding streets
Separation angle ≃ 100
Stagnation angle ≃ 0
vortex dislocations

15. Conclusion
The effect of Reynolds number on the flow past bluff body is extensive
on many phenomenon pertinent to the flow.
Re α Vortices frequency (fp)
Re α cyclic Length (Lc)
Re α
Re α

16. Future work
• To invistigate further flow regimes expermentally and numircally.
• To invistigate further phenomenon using another expermental methods.
• To investigate the applications related to von Kármán vortex shedding.

17. Thank you for your attention!