# Start with Equation IVb.2.8 and obtain Equation IVb.2.9. For this purpose, first ignore the…

Start with Equation IVb.2.8 and obtain Equation IVb.2.9. For

this purpose, first ignore the non-linear term compared with the two dominant

terms. Then substitute for the velocity and temperature profiles. To develop

the integral, consider a case where the hydrodynamic boundary layer is thicker

than the thermal boundary layer (thus the integral is zero for y > _).

Arrange the result in terms of _ = _/_ and ignore _ 4.