Correlation Studies of Pressure Fluctuations on the Ground Beneath a Turbulent Boundary Layer
Correlation Studies of Pressure Fluctuations on the Ground Beneath a Turbulent Boundary Layer
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Date
1965
Authors
Priestley, Joseph Tant
Advisor
Faller, Alan J.
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Abstract
Narrow-band pressure correlation measurements in the frequency range
,008 to 1 Hz(cps) were obtained from a cross spectral analysis between
pairs of microphones placed on level ground beneath the wind stream.
The measurements were made over a range of wind speeds from 2.1 to
7.2 meters per second and a range of hemispheric solar radiation conditions
varying from 0 to 44 Langleys per hour. Plausibility arguments
are presented which predict for the narrow-band longitudinal and
lateral correlation coefficients: -0'~ Rw(£,0) = e cos(kg) and Rw(O~~) =
e-S~ where~ and~ are the longitudinal and lateral separations, respectively,
and 0', S, and k are determined by the experiment. Contrary
to similarity considerations ct and k were found not to be strictly
proportional, but rather 0' = 0.4lk
1
'
28
, 0' and k being expressed in
(meters)-1 , over a range 2 < (1/ot) < 500 meters. The relation between
2 .74 Q -1
ct and S was found to be: ~ = 1. 0' , 0' and ~ expressed in (meters) ,
over a range 3 < (1/~) < 500 meters. For an arbitrary angle with
respect to wind direction evidence is presented which indicates that
Rw(~,~) is very slightly larger than the product Rw(g,O)Rw(O,~). A
small amount of data taken relating the convection velocity versus
wavelength to anemometer readings indicates the possibility of predicting
the wind profile from pressure fluctuations on the ground.