Klebanoff reports roughlv isotropic dissipation for .05 < — < 1.0. which includes 



S 

 this position. 



Shear Spectrum 



Since elementary dimensional reasoning has had a bit of success in predicting 

 the character of local regions in the energy spectrum, it seems natural to attempt the 

 simplest kind of dimensional argument on the shear spectrum, r^k^ defined by 



-uv=j n(fci) dki. (22) 



We are interested in predicting from gross turbulence data the wave number above 

 which the coefficient of shear correlation k R uv is much less than unity. If F^k^ and 

 F 2 {k 1 ) are the one-dimensional spectra of u- and v 2 , 



k x R U v(ki) = 



(23) 



V F x • F,' 

 and this has been measured in several flows [5, 7, 16, 17]. 



For large Reynolds number we naively assume that at the "small eddy" end of 



dU 

 the shear spectrum, ti(&i) depends primarily upon the local mean velocity gradient — . 



dy 

 Then, dimensionally, 



/ dU\ 2 

 \dy / 



SPECTRUM OF SHEAR CORRELATION COEFFICIENT 



[ Stra./jht ///ie s/ope = — ^j ] 



/.00 



.80 



,R U 



./o 

 .08 

 .06 



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386 



