Coherent structure generation in near-wall turbulence

On coherent structure in wall turbulence

Coherent structures in wall-bounded turbulence.

The inherent difficulty of understanding turbulence has led to researchers attacking the topic in many different ways over the years of turbulence research. Some approaches have been more successful than others, but most only deal with part of the problem. One approach that has seen reasonable success (or at least popularity) is that of attempting to deconstruct the complex and disorganised tur...

Large-scale influences in near-wall turbulence.

Hot-wire data acquired in a high Reynolds number facility are used to illustrate the need for adequate scale separation when considering the coherent structure in wall-bounded turbulence. It is found that a large-scale motion in the log region becomes increasingly comparable in energy to the near-wall cycle as the Reynolds number increases. Through decomposition of fluctuating velocity signals,...

Nonlinear RDT theory of near-wall turbulence

A WKB method was recently used to extend rapid distortion theory (RDT) to initially inhomogeneous turbulence strained by irrotational mean flows [S.V. Nazarenko, N. Kevlahan, B. Dubrulle, J. Fluid Mech. 390 (1999) 325]. This theory takes into account the feedback of turbulence on the mean flow, and it was used by Nazarenko et al. to explain the effect of strain reduction caused by turbulence ob...

Low-dimensional dynamics of near-wall turbulence

Wall-bounded turbulent shear flows are perhaps the last area in ‘classical’ incompressible turbulence in which there still are open questions about basic physical mechanisms. There are two competing conceptual models. In the first one, wall turbulence is just a modification of ordinary shear turbulence occuring when the latter is a near wall, and is therefore dependent on the prior existence of...