Boundary Layer Flow Regimes
A boundary layer forms near a surface where fluid velocity changes from zero at the surface to the free stream velocity. The nature of this flow is not fixed.
Flow Characteristics
- Initially, near the leading edge of a surface, the boundary layer flow is typically smooth and orderly, known as laminar flow.
- As the fluid moves along the surface or under certain conditions (like surface roughness or high velocity), the laminar flow can become unstable and break down into chaotic, swirling eddies. This is known as turbulent flow.
- Therefore, the flow within the boundary layer can exist in either of these states.
The flow regime depends on factors like fluid velocity, viscosity, surface geometry, and distance from the leading edge. Transition from laminar to turbulent flow is a common phenomenon.
Conclusion: The flow within the boundary layer can be either laminar or turbulent.
Important Questions from Boundary Layer Theory
Friction drag is generally larger than the pressure drag in _______.
When a fluid flows along a solid boundary, more and more fluid gets retarded in the vicinity of the boundary. This deceleration is accompanied by:
A plate of 500 mm × 200 mm has been placed longitudinally in a stream of an oil which flows with a velocity of 1.0 m/s. The kinematic viscosity of the oil was 0.5 stoke. The thickness of the boundary layer at the trailing edge is _______.
As defined by Prandtl, in convective heat transfer, a thin layer next to the wall where shear stress is confined is called _____.
Thickness of laminar boundary layer on flat plate:
