ABSTRACT
For forced convection, the Nusselt number correlations are
always expressed in terms of two other dimensionless
numbers: the Reynolds number, Re, and the Prandtl num-
ber, Pr. For most cases of forced convection, the general
form of the correlation is
Nu ¼ aRebPrc (4)
where a, b, and c are numerical constants that reflect
the particular conditions that prevail. The Reynolds num-
ber and Prandtl number quantify the behavior of the fluid
close to the solid surface of interest. They can be either
calculated from fluid properties or read from tables. Fluid
properties are usually evaluated at a temperature known as
the film temperature, which is equal to the average of the
solid and fluid temperatures. Knowing their magnitudes
and the appropriate values of the three constants, the
Nusselt number can be determined.
