Boundary Layer flow — Lesson 5

This lesson covers the fundamental concept of the boundary layer in fluid dynamics, focusing on its association with viscous flow. It explains the formation of a thin layer over a flat plate where viscous effects are significant. The lesson also discusses the concept of 'no slip condition' and the difference between inner and outer flow. It introduces the boundary layer thickness and how it is mathematically defined. The lesson further elaborates on the work of Ludwig Prandtl and his boundary layer theory, and the concept of self-similar velocity profiles within the boundary layer introduced by Blasius. It concludes with a discussion on the displacement thickness in the boundary layer.

Video Highlights

01:07 - Explanation of the boundary layer concept with the help of a flat plate example.
06:23 - Discussion on the free stream Reynolds number.
10:15 - Discussion on the order of magnitude analysis of Navier Stokes equations.
17:30 - Explanation of the compressible boundary layer.
23:54 - Explanation of the growth of the boundary layer.
26:52 - Introduction to the concept of displacement thickness in the boundary layer.

Key Takeaways

- The boundary layer is a thin region formed over a flat plate where viscous effects are significant.
- The 'no slip condition' refers to the velocity of the flow being zero on the surface of the plate.
- Ludwig Prandtl proposed the boundary layer theory based on an order of magnitude analysis of Navier Stokes equations.
- Blasius introduced the concept of self-similar velocity profiles within the boundary layer.
- The displacement thickness in the boundary layer refers to the distance by which the external potential flow is displaced outwards due to the decrease in velocity within the boundary layer.