Turbulence

Turbulence or Turbulent flow is a flow regime characterized by low momentum diffusion, high momentum convection, and pressure and velocity variation with time. It is opposed by laminar flow. The (dimensionless) Reynolds number characterizes whether flow conditions lead to laminar or turbulent flow.

Table of contents

1 Examples of turbulence
2 See also
3 External Links

Examples of turbulence

A faucet goes from

Off. No flow
Drip. Which would be modeled as a free boundary problem
Laminar flow. A smooth and regular flow which looks somewhat solid because the flow maintains a fixed shape. In this regime, the water acts as a transparent lens.
Turbulent flow. At a certain point the water will start to break up. The water no long stays contained in a stable region is space. The stream ceases to be transparent.

A drop of cream in a cup of coffee.
Smoke from a smokey candle.

Anecdote: a famous scientist was asked what he would ask God, given the opportunity. His laconic reply was: "Why turbulence?"