Turbulence

Turbulence is a complex phenomenon in fluid dynamics that is often described as chaotic or irregular flow. Despite its complexity, it is a fundamental concept in many areas of physics and engineering, including meteorology, aeronautics, and oceanography.

Overview

Turbulence is characterized by a non-linear set of mathematical equations that describe the motion of fluid. These equations, known as the Navier–Stokes equations, cannot be solved exactly, but can be approximated using numerical methods. Turbulence is often observed in nature, such as in the atmosphere and oceans, and is also important in many engineering applications, including the design of aircraft and ships.

Characteristics

Turbulence is characterized by several key features, including:

• Irregularity: Turbulence is inherently unsteady and unpredictable. It is characterized by a seemingly random and chaotic behavior.

• Diffusivity: Turbulence enhances the mixing and spreading of substances. This is why a puff of smoke disperses quickly in a turbulent air flow.

• Large Reynolds number: Turbulence typically occurs at high Reynolds number, a dimensionless quantity that describes the ratio of inertial forces to viscous forces.

• Three-dimensional vorticity fluctuations: Turbulence is characterized by vortices at many scales. These swirling motions of fluid are a key feature of turbulent flow.

Mathematical description

The mathematical description of turbulence is provided by the Navier–Stokes equations. These equations are a set of partial differential equations that describe the motion of fluid substances. However, these equations are non-linear and cannot be solved exactly for turbulent flow. Instead, various approximation methods are used, such as direct numerical simulation, large eddy simulation, and Reynolds-averaged Navier–Stokes equations.

See also

• Laminar flow
• Vortex
• Eddy
• Reynolds number

References

Turbulence Resources
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