Transition,turbulence and oscillating flow in a pipe a visual study |
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Authors: | L S Fishler R S Brodkey |
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Institution: | (1) 606 Solano Circle, 92670 Placentia, CA;(2) Dept. of Chemical Engineering, The Ohio State University, 140 W. 19th Ave., 43210-1180 Columbus, OH |
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Abstract: | Transitional and turbulent oscillatory flow in a rigid pipe with long entry sections was investigated using flow visualization to establish the existence of coherent structures. Flow tracer and high speed motion pictures were used. The simple harmonic motion of a scotch yoke and flywheel linked to a piston and cylinder provided the flow driving force. The camera was convected with the flow by attaching it through a gearing system to the scotch yoke.List of symbols
A
cross sectional area of flow
-
C, K
constants
-
D
pipe diameter
-
N
Re,ave
Reynolds number based on average velocity (DU
ave
/v)
-
N
Re,p
Reynolds number based on maximum oscillatory velocity (DU
max
/v)
-
Reynolds number based on maximum oscillatory velocity and Stokes (boundary) layer thickness (U
max
/v)
-
R
pipe radius
-
U
instantaneous velocity in the flow direction
-
short-term average instantaneous velocity
-
U
*
friction velocity (U
ave
(f/2)1/2)
-
U
amp
amplitude parameter (U
max
/U
ave
)
-
U
ave
average velocity
-
U
s
steady velocity
-
U
t
instantaneous oscillatory velocity
-
U
max
maximum oscillatory velocity ( X
max
/T)
-
u
r
, u
z
deviations from r, and z
-
y
radial coordinate from wall (R–r)
-
y
+
dimensionless radial coordinate from wall (y U*/v)
-
frequency parameter R (/v)
1/2]
-
Stokes (boundary) layer thickness C (2 v/)1/2]
-
normalized time into cycle
-
fluid viscosity
-
v
fluid kinematic viscosity (/)
-
density
-
angular frequency (2/T)
- -
overbar, average
-
sub-c
critical value |
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Keywords: | |
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