19. Laminar and Turbulent Flow (Contd.)
The chapter focuses on shear stresses in turbulent flow, detailing the Boussinesq model which introduces the concept of eddy viscosity. It discusses Reynolds' shear stress theories and Prandtl's mixing length theory, highlighting how shear stress in turbulent flows is significantly influenced by turbulence. Furthermore, it elucidates the relationship between kinematic quantities and flow characteristics in fluid dynamics, particularly in pipes.
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Sections
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1.1Lecture- 15
What we have learnt
- Shear stress in turbulent flow includes components from both viscosity and turbulence.
- Eddy viscosity and kinematic eddy viscosity are crucial in understanding turbulent flow behavior.
- Reynolds shear stress involves fluctuating velocity components and can be calculated using Prandtl's mixing length theory.
Key Concepts
- -- Eddy Viscosity
- A coefficient that describes the turbulent shear stress in a fluid and varies with flow conditions.
- -- Reynolds Shear Stress
- The shear stress due to turbulence, expressed as the average of the product of velocity fluctuations in perpendicular directions.
- -- Mixing Length Theory
- A concept introduced by Prandtl that relates turbulence characteristics in a fluid to the average velocity gradient and distance from the wall.
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