Thermal Boundary Layer

The thermal boundary layer is a fluid boundary layer that is measures the temperature of a fluid as it flows over a surface. The concentration boundary layer is essentially the same thing but it measures mass instead.

Heavily related to velocity boundary layer.

The thermal boundary layer thickness, , increases the further it is down the flow direction.

Heat flux given by the following:

Using this we can find an expression for the convection heat transfer coefficient. If is greater than then:

Then plugging this into our equation for heat flux we get:

See ME3304 S24 Lecture Note (3) Convection for more info.

Equation 6.14:

ME3304 S24 Lecture Note (3) Convection - Page 10

The derivation of Equation 6.14 is shown in 9A - 2nd Class.