Turbulence:

Turbulence, In fluid mechanics, a flow condition (see turbulent flow) in which local speed and pressure change unpredictably as an average flow is maintained. Common examples are wind and water swirling around obstructions, or fast flow (Reynolds number greater than 2,100) of any sort. Eddies, In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to laminar flow, which occurs when a fluid flows in parallel layers with no disruption between those layers. [1] Turbulence is everywhere—in the interiors and atmospheres of planets and stars, galaxies, biological systems including human body, engineering flows, etc. In this course, we will cover fundamental aspects of turbulence—Kolmogorov’s theory of turbulence in spectral and real space; two-dimensional turbulence; energy transfers; enstrophy and kinetic helicity cascades; more complex applications, such as passive scalar, turbulent thermal convection, and magnetohydrodynamic turbulence. The physical attributes of turbulent flow, in and of itself is a very difficult subject. That is to say, the flow characteristics of turbulence are difficult to measure, difficult to interpret and very difficult to incorporate into analyses. Never-the-less progress has been made, but much of it relies heavily on empirical results. Turbulence is typically described as a time varying phenomena of all dependent variables (except density for incompressible flows). In addition, spatial variations ...