<DOC>
<DOCNO>
872
</DOCNO>
<TITLE>
fundamentals of boundary layer heat transfer with streamwise
temperature variations .
</TITLE>
<AUTHOR>
biot,m.a.
</AUTHOR>
<BIBLIO>
j. ae. scs. 1962, 558.
</BIBLIO>
<TEXT>
  boundary-layer heat transfer is analyzed for the case of a sinusoidal
distribution of temperature in the direction of flow .  it is
shown that for both laminar and turbulent flow the spatial distribution
of heat transfer is generally out of phase with the wall
temperature by an angle of 30 to 45 .  this leads to the conclusion
that in some areas the heat flow is opposite to the temperature
difference as used in the definition of the heat-transfer
coefficient, and points to the basic shortcomings of this concept .
the physical explanation for this behavior is found to be the
temperature-field distortion by the fluid motion .  the distortion
is measured by the peclet number .  approximate equations
representing a /conduction analogy/ were used in this analysis
and the validity of these equations for unsteady flow is examined
with reference to limitations in frequency and wavelength .  a
solution of these equations is given for the case of a velocity profile
which is not a straight line .  the use of previously developed
variational principles for the evaluation of convective heat
transfer including cases of three-dimensional unsteady flow,
turbulence, and nonparallel streamlines is also discussed .
</TEXT>
</DOC>
