TR No. 22 
At K= 0.01 cm™+ the average value of the computed energy spectra is 
P an (kK) = 9,15 x 10° cm°-sec™“, 
It is necessary to have a value for the universal constant K'. If 
the value obtained by Grant, et al (2) is used, then the average value 
of K' is 0.47 10.02 (standard error). Substituting this value along 
with the average value of @,,, (&) into equation (13), 
ae 9.15 x 107 | Yes (G10 ene sace 
(ORE) (OER ES OS) 
The result is of the same order of magnitude as the values reported in 
reference 2, No attempt has been made to determine € for the individual 
spectra because of the statistical variations. The individual spectra would, 
in general, yield different values of € 3; because of inhomogeneity of the 
field of turbulence, € is a function of position as well as time. 
CONCLUSIONS 
1. The ducted impeller current meter, with a constant wave number 
response of from 0 cm ~ to 0.0353 cm, is a practical instrument for 
measuring oceanographic turbulence. The high wave number response is 
limited by the dimensions of the current meter instead of the response 
distance (also constant), measured as 0.75 cm. The data obtained from 
the instrument are approximately equally spaced at intervals of 19.61 am, 
resulting in a Nyquist wave number of 0.157 cml; the sampling process 
further attenuates velocity variations at wave numbers greater than the 
Nyquist wave number. Since the Nyquist wave number is greater than the 
highest wave number at which the current meter is responsive to velocity 
variations by a factor of four, aliasing is negligible. 
2. The average sample variance is 55.6 om?-sec72 +25,0 (standard error). 
Superficial comparison of the distribution of the values of the energy spectra 
with the expected Chi-Square distribution, however, indicated that the variation 
is statistical. The variation is attributed primarily to short sample lengths 
and inhomogeneity of the field of turbulence. 
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