The hydrodynamic boundary layer thickness is defined as the distance from the surface where the
Hydrodynamic boundary layer thickness is defined as the distance measured in the y direction from boundary to the point where the velocity is 99% of the free stream velocity.
Laminar boundary layer thickness (δ) at any point x for flow over a flat plate is given by δ/x
From the Blasius solution
The velocity profile for turbulent layer over a flat plate is
Turbulent velocity profile follows 1/7 power law, hence
will be velocity distribution.
The turbulent boundary layer thickness varies as
For turbulent flow
According to Blasius, the local skin friction coefficient in the boundary layer over a flat plate is given by
Local skin friction coefficient
The thickness of laminar boundary layer at a distance 'x' from the leading edge over a flat plate varies as
The Von-karman momentum integral equation expressed as (where θ is momentum thickness)
Von-karman momentum integral equation is expressed as
Consider the following statements:
Boundary layer separation is caused by:
1. An adverse pressure gradient
2. Sudden entrapping of air
3. Reduction of pressure gradient to zero
4. Release of bubbles from the fluid when the pressure goes below the vapor pressure
Q. Which of the above statements is/are correct?
Air flows past a golf bail of 20 mm radius. It is observed that the boundary layer becomes turbulent at Reynolds number of 2 x 105. If the kinematic viscosity of air is 1.5 x 10-5 m2/sec then the speed of air when the flow becomes turbulent is
Blasius equation for a flat plate laminar boundary layer flow is a third order