Richarson kolmogorov onsager cascade spectral

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: RICHARSON-KOLMOGOROV-ONSAGER, CASCADE /spectral RICHARSON transfer - ill defined. TAYLOR, Vorticity amplification is a result of the kinematics of turbulence : TAYLOR vortex lines are on average stretched rather than compressed because two particles on average move apart from each other – RRWR . Is enhanced dissipation due to predominant vortex stretching? BATCHELOR, For the very smallest eddies the motion is entirely laminar. BATCHELOR, _____________________________________ _____________________________________ *Unlike other, e.g. involving cascade. Representation versus process. *Passive objects, low-D systems ONE MORE ‘SIMPLE’ EXAMPLE The energy dissipation in turbulent flows remains finite at whatever Reynolds number, i.e. inertial and dissipative the effects/terms are of the same order # Similarly the enstrophy and strain production are are of the same order as their viscous destruction/‘disspiation’ and even are approximately balanced. # Turbulence is not a slightly viscous/dissipative phenomenon! Turbulence Hence there is problem with statements like (you are welcome to discuss this in more detail) • Reynolds number represents the ratio of inertial to viscous forces. • For large Re the viscous interactions turn out to be quite weak. • At large Re flow perturbations produced at scale L experience a viscous dissipation that is small compared with nonlinear effects. Nonlinearity then induces motions at smaller and smaller scales until viscous dissipation terminates the process at a scale much smaller than L, leading to a wide (so-called inertial) interval of scales where viscosity is negligible and non linearity plays a dominant role. The problem with misconceptions starts with the question The What is turbulence? and the attempts to give a definition of what turbulence is? Are such attempts conceptually correct? In a mathematical theory the definition of the main object of the theory precedes the results; In physics, especially in new fields, it i...
View Full Document

This note was uploaded on 09/16/2011 for the course ME 563 taught by Professor Staff during the Spring '11 term at Auburn University.

Ask a homework question - tutors are online