Thermal Boundary Layer

Since the heat transfer by convection involves the motion of fluid particles, we must superimpose the temperature field on the physical motion of fluid and the two fields are bound to interact.

• It is intuitively evident that the temperature distribution around a hot body in a fluid stream will often have the same character as the velocity distribution in the boundary layer flow.
• When a heated solid body IS placed in a fluid stream, the temperature of the fluid stream will also vary within a thin layer In the immediate neighbourhood of the solid body.
• The variation in temperature of the fluid stream also takes place in a thin layer in the neighbourhood of the body and is termed 'thermal boundary layer'.

Following figure shows the temperature profiles inside a thermal boundary layer.

The thermal boundary layer