Features of Turbulence

1. Turbulence is irregular and seemingly random (chaotic). Statistical methods should be used for extracting useful engineering information.
2. Turbulence is highly diffusive. Rapid mixing significantly increases momentum, heat, and mass transfer.
3. Turbulence is rotational and three-dimensional motion.
4. Turbulence is associated with high levels of vorticity fluctuation. Smaller scales are generated by the vortex stretching mechanism.
5. Turbulence is highly dissipative. It needs a source of energy to be maintained.
6. Turbulence is a continuum phenomenon. The smallest scale of turbulence is much larger than the molecular scales in most engineering applications.
7. Turbulence is a manifestation of flow and not of the fluid.
8. The mean field fluid is non-Newtonian, viscoelastic, memory-dependent, multi-temperature, nonlocal, and contains several internal variables.

Origin of Turbulence

Turbulence is associated with high Reynolds number. Its origin is rooted in the instability of shear flows. Turbulence is also generated in buoyancy driven flows.