On the effects of a periodic, spanwise variation of suction upon asymptotic suction flow |
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Authors: | R E Kelly |
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Affiliation: | (1) Dept. of Engineering, University of California, Los Angeles, USA |
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Abstract: | Summary The effects of superposing streamwise vorticity, periodic in the lateral direction, upon two-dimensional asymptotic suction flow are analyzed. Such vorticity, generated by prescribing a spanwise variation in the suction velocity, is known to play an important role in unstable and turbulent boundary layers. The flow induced by the variation has been obtained for a freestream velocity which (i) is steady, (ii) oscillates periodically in time, (iii) changes impulsively from rest. For the oscillatory case it is shown that a frequency can exist which maximizes the induced, unsteady wall shear stress for a given spanwise period. For steady flow the heat transfer to, or from a wall at constant temperature has also been computed.Nomenclature (x, y, z)
spatial coordinates
- (u, v, w)
corresponding components of velocity
- (, , )
corresponding components of vorticity
-
t
time
-
stream function for v and w
-
v
w
mean wall suction velocity
-
nondimensional amplitude of variation in wall suction velocity
-
characteristic wavenumber for variation in direction of z
-
T
temperature
-
P
pressure
-
density
-
coefficient of kinematic viscosity
-
coefficient of thermal diffusivity
-
(/v
w)2
-
frequency of oscillation of freestream velocity
-
nondimensional amplitude of freestream oscillation
-
/v
w
2
-
z
z
-
y
–v
w
y/
-
v
w
2
t/4
-
/v
w
-
U
0
characteristic freestream velocity
-
u/U
0
-
coefficient of viscosity
-
w
wall shear stress
-
Prandtl number (/)
-
q
heat transfer to wall
-
T
w
wall temperature
-
T
(T
w–T)/(T
w–) |
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Keywords: | |
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