IntermediateTopic 56 of 105Thermodynamics & Fluids
Laminar and turbulent flow
Smooth layers versus chaotic mixing; predicted by Reynolds number.
In depth
Laminar flow is smooth with parallel layers (Re<2300 in pipes), transitional between about 2300 and 4000, and turbulent beyond with chaotic mixing, higher friction and heat transfer. Velocity profile is parabolic in laminar pipe flow, flatter in turbulent.
Key points
- Hagen-Poiseuille for laminar
- Mixing enhances heat transfer
- Turbulence intensity
ExampleSmoke from incense rises smoothly then breaks into eddies.
Laminar and turbulent flow change friction, mixing and heat transfer, so you must know which regime applies to a given flow.
What is Laminar and turbulent flow?
Smooth layers versus chaotic mixing; predicted by Reynolds number.
Why is it important to understand laminar and turbulent flow?
Laminar and turbulent flow change friction, mixing and heat transfer, so you must know which regime applies to a given flow.
What makes a flow laminar?
Smooth, orderly layers that slide past each other with viscosity damping disturbances, typically at low Reynolds number.
What makes flow turbulent?
Inertia dominates and small disturbances grow into chaotic eddies, which increase mixing and friction.
How is Laminar and turbulent flow used in practice?
Typical applications include predicting the mixing of a dye in a turbulent river against laminar flow in a viscous oil line, choosing the flow regime for a chemical reactor to improve mixing and recognising laminar flow in a small microfluidic channel.
What should I learn before Laminar and turbulent flow?
Study "Momentum equation" first (topic 55 of 105 in Thermodynamics & Fluids). It covers the groundwork this topic builds on.
What are the key points of Laminar and turbulent flow?
Hagen-Poiseuille for laminar. Mixing enhances heat transfer. Turbulence intensity.
Can you give an example of Laminar and turbulent flow?
Smoke from incense rises smoothly then breaks into eddies.
What comes after Laminar and turbulent flow?
The next topic is "Reynolds number", which builds directly on this one.
How difficult is Laminar and turbulent flow?
It is classed as Intermediate in Thermodynamics & Fluids (topic 56 of 105). It is an intermediate topic. Work through the beginner topics in Thermodynamics & Fluids first.