A numerical investigation of a 2D flow passage the whole domain of which is subdivided into a viscosity-affected laminar layer and a fully-turbulent layer is presented. The calculated results indicate that the angles between temperature gradient and velocity in the laminar layer influences heat transfer in the whole turbulent layer. They can enhance heat transfer

reduce heat transfer coefficient

or have no effect on it. Enhanced heat transfer on the coarse wall is analyzed with the Field-Synergy theory while water is in fully-developed turbulent flow.