  A new two-layer model has been proposed to study microscale heat transfer
associated with a developing flow boundary layer. As an example, a cold,
microscale film of liquid impinging on an isothermal hot, horizontal surface
has been investigated. The boundary layer is divided into two regions: a micro
layer at microscale away from the surface and a macro layer at macroscale away
from the surface. An approximate solution for the velocity and temperature
distributions in the flow along the horizontal surface is developed, which
exploits the hydrodynamic similarity solution for microscale film flow. The
approximate solution may provide a valuable basis for assessing microscale flow
and heat transfer in more complex settings.
