Question

Compare hydrodymic and thermal boundary layer

Answer 1

Answer:

For a flow domain, boundary layer is the region near to the wall where wall effects are significant. Hydrodynamic boundary layer refers to the region close to the wall in which viscosity affects the fluid velocity. Similarly thermal boundary layer refers to the region where wall temperature affects the fluid temperature. Outside the boundary layer wall effects are negligible and free stream conditions prevail. Thus within the hydrodynamic boundary layer fluid velocity varies from zero at the wall to free stream at the edge of boundary layer. Within the thermal boundary layer, temperature of fluid varies from wall temperature to free stream at the edge of boundary layer.

The link between the two is the Prandtl number!!

For Pr = 1 thickness of velocity and thermal boundary layers is same.

Explanation: