The average friction coefficient and Nusselt number are expressed in functional form as

$C_f$=$f_4$ ($Re_L)$ and Nu=$g_3$ ($Re$_L,Pr)

The Nusselt number can be expressed by a simple power-law relation of the form

Nu=C$Re_L^m$ $Pr^n$

Where m and n are constant exponents, and the value of constant C depends on geometry. …