The Convection Boundary layers Thermal Boundary layer(contd) Heat Flux(Contd USing Newton's law of cooling q"=h(ts We obtain h=-k,0m/o- While 8 increases with increasing x, temperature gradients in the boundary layer must decrease with increasing x Accordingly sand h decrease with increasing X Heat Transfer Su Yongkang School of Mechanical EngineeringHeat Transfer Su Yongkang School of Mechanical Engineering # 12 The Convection Boundary Layers Thermal Boundary Layer (Cont’d) Heat Flux (Cont’d) • Using Newton’s law of cooling: We obtain • While  increases with increasing x, temperature gradients in the boundary layer must decrease with increasing x. • Accordingly, and h decrease with increasing x. ( ) = −  q  h Ts T  = − −   = T T k T y h s y f 0 / s q 