What is hydrodynamic and thermal boundary layer?
This thin layer of changing velocity has been called the hydrodynamic boundary layer; a concept first suggested by Ludwig Prandtl in the year 1904. Heat transfer occurs due to heat conduction and energy transport by moving fluid within this thin layer.
What is the difference between hydrodynamic and thermal boundary layer thickness?
The thickness of the hydrodynamic boundary layer (velocity boundary layer) is normally defined as the distance from the solid body at which the viscous flow velocity is 99% of the free stream velocity. If the Prandtl number (Pr) is 1, the two boundary layers (hydrodynamic and thermal) are the same thickness.
What is difference between thermal boundary layer and hydrodynamic boundary layer?
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.
What are the velocity and thermal boundary layers?
Similarly as a velocity boundary layer develops when there is fluid flow over a surface, a thermal boundary layer must develop if the bulk temperature and surface temperature differ.
Which is true for two dimensional boundary layer?
Which is true for two dimensional boundary layer? Explanation: It is steady incompressible flow. The temperature of the fluid changes from a minimum at the plate surface to the temperature of the mainstream at a certain distance from the surface.
What is meant by hydrodynamic boundary level?
This region within which the flow is disturbed is therefore larger for highly viscous fluids. This area where the flow velocity is disturbed by the influence of shear stresses between the fluid layers, is also called velocity boundary layer or hydrodynamic boundary layer.
What is skin friction coefficient?
The skin friction coefficient is an important dimensionless parameter in boundary-layer flows. It specifies the fraction of the local dynamic pressure, 1 2 ρ U 2 , that is felt as shear stress on the surface.
What conditions are necessary for the development of a hydrodynamic boundary layer?
A thermal boundary layer that determines the thermodynamic interaction of heat transfer is necessary for the development of a hydrodynamic boundary layer. If convection heat transfer for flow of a liquid or a vapor is not characterized by liquid / vapor phase change, what is the nature of the energy being transferred?