Where \(\tau_w\) is the surface shear stress and \(q_w\) being surface heat defined as following way:
\[\tau_w=\mu\left(\frac{\delta u}{\delta y}\right)_{y=0},\ and\ \ q_w=-k\left(\frac{\delta T}{\delta y}\right)_{y=0}\]
By using (16) and (17), equation (15) reduces to