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A youtube video made by me explaining how to simulate a flow over an airfoil: https://goo.gl/9VYRFM
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Ahmed Gaber Ahmed
Esraa Mahmoud Saleh
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circular cylinders were the most interested sections to study the vortex shedding phenomenon. The Vortex Shedding
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steadiness.In the present work CFD simulation is carried out for flow past a D-Shaped cylinder to see the wake
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surface. The experimentation is carried out using small open type wind tunnel. The flow visualization is done by
smoke visualization technique. Results are presented for various B/H ratios and Reynolds numbers. The variation of
Strouhal number with Reynolds number is found from the analysis. The focus of the present research is on reducing
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This report is a simulation for a flow over an airfoil "NACA 0009" at Reynolds number equals 1 million for four angles of attack using three different turbulence models and of cause a grid independence solution.
The goal of this study is to apply the knowledge obtained from studying in the university and self-learning in order to solve a specific task of finding the coefficient of drag and lift for the airfoil.
A youtube video made by me explaining how to simulate a flow over an airfoil: https://goo.gl/9VYRFM
Team members:
Ahmed Kamal Shalaby
Ahmed Gaber Ahmed
Esraa Mahmoud Saleh
The flow across an airfoil is studied for different angle of attack. The CFD analysis results are documented and studied for different angle of attack using fluent & gambit.
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CFD and EXPERIMENTAL ANALYSIS of VORTEX SHEDDING BEHIND D-SHAPED CYLINDERAM Publications
The flow around bluff bodies is an area of great research of scientists for several years. Vortex shedding is
one of the most challenging phenomenon in turbulent flows. This phenomenon was first studied by Strouhal. Many
researchers have modeled the various objects as cylinders with different cross-sections among which square and
circular cylinders were the most interested sections to study the vortex shedding phenomenon. The Vortex Shedding
frequency depends on different aspects of the flow field such as the end conditions, blockage ratio of the flow passage,
and width to height ratio. This case studies the wave development behind a D-Shaped cylinder, at different Reynolds
numbers, for which we expect a vortex street in the wake of the D-Shaped cylinder, the well known as von Kármán
Street. This body typically serves some vital operational function in aerodynamic. In circular cylinder flow separation
point changes with Reynolds number but in D-Shaped cylinder there is fix flow separation point. So there is more
wake steadiness in D-Shaped cylinder as compared to Circular cylinder and drag reduction because of wake
steadiness.In the present work CFD simulation is carried out for flow past a D-Shaped cylinder to see the wake
behavior. The Reynolds number regime currently studied corresponds to low Reynolds number, laminar and
nominally two-dimensional wake. The fluid domain is a two-dimensional plane with a D-Shaped cylinder of
dimensions B=90mm, H=80mm and L=200mm. CFD calculations of the 2-D flow past the D-Shaped cylinder are
presented and results are validated by comparing with Experimental results of pressure distribution on cylinder
surface. The experimentation is carried out using small open type wind tunnel. The flow visualization is done by
smoke visualization technique. Results are presented for various B/H ratios and Reynolds numbers. The variation of
Strouhal number with Reynolds number is found from the analysis. The focus of the present research is on reducing
the wake unsteadiness.
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CFD technology offers an appealing option to help in the design and
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1935 – Heil oscillator
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1) extended interaction klystron
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VOLTAGE-TUNABLE
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The current research study was developed by a collaboration between BMT Fluid Mechanics Ltd and the University of Genoa and will focus on the aerodynamic behaviour of super slender towers. Super slender are becoming more and more popular among the residential real estate market and this is a consequence of the fact that the world’s population will tend to concentrate in large cities where there is limited availability of space and price of land can be impressively high. Therefore, the increasing necessity to build taller and slender buildings which are lighter, more flexible and with less structural damping will push engineers and architects to collaborate together in the wind tunnel to find new optimized aerodynamic solutions in order to overcome the intrinsic vulnerability to wind action these kind of structures carry. A representative example of a built super slender structure is 432 Park Avenue in New York, completed in 2015 with an aspect ratio of 15 to 1.
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Latest 2014 development of the Spiral Magnetic Motor (SMM) which uses only permanent magnets. This is a work in progress with joint contributors including a physics professor and at least one student. We are encouraged by the fact that for any given volume, magnetic energy exceeds any possible electrical field in air by 50,000. In addition, magnets are also powered by spinning electrons which are sustained by the quantum vacuum and a physics journal article is also in the works to explain the operation as it nears completion. More information at www.integrityresearchinstitute.org
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The Mechanism of Aeroelastic Vibration on 2-Edge-Girder Bridge by CFD
1. Soulachack SOUKSIVONGXAY
The Mechanism of Aeroelastic Vibration on
2-Edge-Girder Bridge by Computational Fluid Dynamics
2013.5.19
数値流体解析によるエッジガーダー橋
の空力弾性振動メカニズム
スラチャック スクシーウォンサイ
2. The Mechanism of Aeroelastic Vibration on
2-Edge-Girder Bridge by Computational Fluid Dynamics
1. About the Bridge Structure
・ the classification of bridge
・ the structural partial of bridge
・ damaged bridges due to natural disaster(EQ, Typhoon…)
2. Wind-Bridge’s Relationship
・ the collapse of Tacoma Bridge
・ wind tunnel experiment & PIV experiment
・ wind-induced vibration’s phenomenon
3. Master Research’s Contents and Results
・ study’s background & purpose
・ analysis results (Static and Dynamic)
・ conclusion
3. ◆ The Classification of Bridge
① Material
concrete bridge, steel bridge, wooden bridge, stone bridge …
② Usage
high way bridge, railway bridge, pedestrian bridge…
③ Road Surface
deck bridge, through bridge, haft through bridge…
④ Support Type
simple bridge, continuous bridge, gerber bridge…
⑤ Structural Type
girder bridge, cable-stayed bridge, suspension bridge, truss
bridge, arch bridge, rigid-frame bridge
5. ◆ The Structural Partial of Bridge
Handrail(高欄)
Slab(床版)
Main Girder
(主桁)
Pier(橋脚)
Bearing
(支承)
girder bridge
Pavement(舗装)
① ② ③
6. ◆ The Collapse of Tacoma Bridge
・wind tunnel experiment & PIV experiment
⇒ to investigate the wind resistance characteristic
・sine 1940 , wind-bridge engineering became to consider
the wind - induced vibration’s phenomenon
Tacoma Suspension Bridge(1940)
・ until 1940, only wind load was
considered to the wind resistance design
・ Tacoma Bridge: under wind load
(≒wind velocity 60m/s) was designed.
but the torsional flutter vibration
was occurred at 19m/s
7. ◆ Wind Tunnel Experiment & PIV Experiment
understand the separated flow,
stream line, reattachment
property…etc,
wind
Wind Tunnel Experiment PIV Experiment
smooth – turbulence flow
(simulate the real wind’s PSD)
psd
frequency
vortex-induced vibration
flutter vibration
disp
wind velocity
:case1
:case2
:case3
bridge’s model
8. vortex-Induced vibration(渦励振), torsional flutter, rain –
vibration, galloping, gust responded vibration…etc,
◆ Wind-Induced Vibration’s Phenomenon
① Vortex-Induced Vibration
vortex’s frequency( )
large negative pressure( )
Hzfst
PaP
wind
Karman Vortex Shedding
external aero-
dynamic force
the periodic external force due to the vortex shedding
is applied on the body surface
⇒ happen at the small wind velocity & limited amplitude
9. ① Vortex-Induced Vibration
vortex’s frequency( )
large negative pressure( )
Hzfst
PaP
wind
External aero-
dynamic force
the periodic external force due to the vortex shedding
is applied on the body surface
⇒ happen at the small wind velocity & limited amplitude
◆ Wind-Induced Vibration’s Phenomenon
vortex-Induced vibration(渦励振), torsional flutter, rain –
vibration, galloping, gust responded vibration…etc,
10. ② Rain Vibration
water route
windrain
wind
cablevibration
the water route generated on the cable surface deform
the cable’s section
⇒ happen at the low wind velocity & light raining
rain
◆ Wind-Induced Vibration’s Phenomenon
Fred Hartman Bridge(America,1995)
vortex-Induced vibration(渦励振), torsional flutter, rain –
vibration, galloping, gust responded vibration…etc,
11. The Mechanism of Aeroelastic Vibration on
2-Edge-Girder Bridge by Computational Fluid Dynamics
1. About the Bridge Structure
・ the classification of bridge
・ the structural partial of bridge
・ damaged bridges due to natural disaster(EQ, Typhoon…)
2. Wind-Bridge’s Relationship
・ the collapse of Tacoma Bridge
・ wind-induced vibration’s phenomenon
・ wind tunnel experiment & PIV experiment
3. Master Research’s Contents and Results
・ study’s background & purpose
・ analysis results (Static and Dynamic)
・ conclusion
12. Edge Girder Bridge a few main girder bridge’s type
construction・economic advantage apply to long-span bridge
Alex fraser bridge(canada・cable-stayed bridge・main span : 460m・1986 complete)
Nanpu bridge(china・cabel-stayed bridge・main span : 423m・1991 complete)
Binh bridge(vietnam・cable-stayed bridge・main span : 260m・2005 complete)
Choshi bridge(japan・cable-stayed bridge・main span192.6m・2010 complete)
the edge girder long-span bridge was adopted
in Japan is very less
13. ❏ investigation by wind tunnel testing:
to clarify the aerodynamic vibration generating ’s
mechanism quantitively is difficult
✓
❏ Problem of Edge Girder Bridge:
low torsional stiffness ⇒ instability of wind-resistant
✓
wind
wind tunnel testing Computational Fluid Dynamic(CFD)
applying the CFD with the wind tunnel testing the efficiency
of wind-stability investigation can be expected more
Edge Girder Bridge a few main girder bridge’s type
bridge model
14. Study’s Purpose:
to clarify the aerodynamic vibration on 2 edge girder-
bridge by using CFD
previous wind tunnel testing(2000)
CFD model(2D・B÷D=10)
D
C
B
❏ Static Analysis
・ 3 components of aerodynamic force coefficient, separated flow –
pattern … etc,
❏ Dynamic Analysis
・ 1DOF torsion・vertical vibration’s unsteady aerodynamic force,
surface pressure distribution … etc,
・ to verify the Separation Interference
Method(SIM)’s effectiveness
θ handrail
C÷D:overhanging ratio
15. ①Stationary Region
②Moving Region(Overset Mesh)
Overlap boundary condition
No-slip(U=V=0)
(body’s surface)
D
B
40D
10D
60D
20D
Moving
・2D(RANS)・重合格子法(Overset Meshing Method)
(the mesh is not change when the body is moving)
tfyty y2sin)( 0
tft 2sin)( 0
C
・forced vibration method
1DOF vertical vibration ⇒
1DOF torsional vibbration ⇒
Moving
Slip (U≠0,V=0)
Inlet(smoothfow)
Outlet(P=0)
inlet flow Smooth flow
torsional angle θ0 0.5~13°
vertical disp y0 0.1D~2.5D
time step(Δt) 0.005s
total of elements 29100~34200
mesh’s division
Mesh①~④
(2.5,5,10,25mm)
Analysis’s Parameters
Mesh①
Mesh② Mesh③
Mesh④Slip (U≠0,V=0)
17. ②
④ ⑥
⑧
negative pressure
positive moment
①
②
③
④
⑤
⑥ ⑧:torsional angle
: pitching moment
t(s)
LM CC ,
0/
⑦
:lift force
positive moment & Lift
Θ
D
C
B
(B÷D=10,C÷D=0.5)
Pressure(Pa)
Smooth Flow: U
upward torsion
downward torsion
excitation force’s situation
(C÷D=0.5・Ur=U/f.D=80)
downward torsion
upward torsion
positive M
negative P
negative P
negative M
negative M
negative P
18. ④ ⑥
⑧
①
②
③
④
⑤
⑥ ⑧:torsional angle
: pitching moment
t(s)
LM CC ,
0/
⑦
:lift force
positive moment & Lift
Θ
D
C
B
(B÷D=10,C÷D=0.5)
Pressure(Pa)
Smooth Flow: U
downward torsion
(C÷D=0.5・Ur=U/f.D=80)
downward torsion
upward torsion
positive M
negative P
negative P
negative M
negative M
negative P
③
negative P
positive M
(Max)
upward torsion
excitation force’s situation
19. ● the separated bubble appeared on the upper surface
(upsteam side) generate the excitation force dominantly
torsional flutter generation’s main cause
Pressure(Pa)
(C÷D=0.5・Ur=U/f.D=80)
④ downward torsion
positive M
negative P
⑥downward torsion
negative P
negative M
⑧ upward torsion
negative M
negative P
③
negative P
positive M
(Max)
upward torsion
excitation force’s situation
20. C÷D=0.5・θ=90° C÷D=0.5・θ=30° C÷D=2.0・θ=90° C÷D=2.0・θ=30°
Instantaneous separated vortex・stream line’s pattern(1DOF torsion,Ur=80)
D
C
handrail
-1.0 1.00.0
B
剥離干渉法(SIM)
aerodynamical damping measure method
(Kubo・JSCE・1992)
suppress the separated flow
1st separated
point
2nd separated point
upper surface unsteady pressure
distribution’s comparison(Ur=80)
2
5.0 U
P
CP
PC
C÷D=0.5
C÷D=2.0
:No handrail :θ=90° :θ=30°
:No handrail :θ=90° :θ=30°
:C÷D=0.5・θ=30°
1DOF torsional vibration ⇒ C÷D=0.5・
θ=30° is the most of SIM effectivenessupper surface
C÷D:overhanging ratio
21. 1. Static Analysis’s Results
using CFD to investigate the aerodynamic vibration on
2 edge girder bridge
1DOF torsional vibration・Ur=80
●
C÷D=0.5 C÷D=2.0
1DOF vertical vibration・Ur=12.5
the static aerodynamic force’s curves are match with the previous
experimental results, C÷D=0.5(outside girder’s installation)
⇒ torsional flutter instability is more decrease
separated bubble
excitation force
2. Dynamic Analysis’s Results
the separated bubble on the upper surface
(upstream side) cause the torsional flutter
●
the separated vortex between
two girders‘ area cause the
vortex shedding vibration
●
● overhanging ratio C÷D=0.5 with handrail (θ=30°) is the most of
Separation Interference method’s effectiveness
22. Soulachack SOUKSIVONGXAY
The Mechanism of Aeroelastic Vibration on
2-Edge-Girder Bridge by Computational Fluid Dynamics
2013.5.19
数値流体解析によるエッジガーダー橋
の空力弾性振動メカニズム
thank you for your kind attention
スラチャック スクシーウォンサイ