KURENAI : Kyoto University Research Information Repository

'
u = (i)l/7
u~ S 1.7(69)
T -TT= 1 - (s)1/7(70)
wt
Here, S v and St are thicknesses of turbulent velocity boundary layer and
turbulent thermal boundary layer repectively. The thickness of velocity
boundary layer is related to the wall shear stress for turbulent flow` which
is given by Eq.(58). Then (5 vis given by
= 0 .380 x Re xO.2(71)
v On the other hand, the eddy diffusivity of momentum,54, is defined by
eMp = do
dy )(72)
Now, one considers the turbulent region near wall where Eq.(69) can
be applicable. In this near wall region, one may approximate shear stress
T;: by wall shear stress, Tw. Based on this assumption, and substituting
Eqs.(58) and (69) into Eq.(72),one obtains,'
cM
()= 0.545(.)(S)6/7(73)
cov
On the other hand, turbulent diffusivity of heat is defined by
£HOPP=dT
(d )(73)
y)
Again, one considers the turbulent region near wall where Eq.(70) can be
applicable. When the heat capacity of the viscous sublayer is much smaller
than the heat capacity of turbulent thermal boundary layer, the heat flux
q, in Eq.(74) can be approximated by wall heat flux, qw, without serious
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