Dynamical interpretation of conditional patterns
Abstract
While great progress is being made in characterizing the 3D structure of organized turbulent motions using conditional averaging analysis, there is a lack of theoretical guidance regarding the interpretation and utilization of such information. Questions concerning the significance of the structures, their contributions to various transport properties, and their dynamics cannot be answered without recourse to appropriate dynamical governing equations. One approach which addresses some of these questions uses the conditional fields as initial conditions and calculates their evolution from the NavierStokes equations, yielding valuable information about stability, growth, and longevity of the mean structure. To interpret statistical aspects of the structures, a different type of theory which deals with the structures in the context of their contributions to the statistics of the flow is needed. As a first step toward this end, an effort was made to integrate the structural information from the study of organized structures with a suitable statistical theory. This is done by stochastically estimating the twopoint conditional averages that appear in the equation for the onepoint probability density function, and relating the structures to the conditional stresses. Salient features of the estimates are identified, and the structure of the onepoint estimates in channel flow is defined.
 Publication:

Studying Turbulence Using Numerical Simulation Databases, 2
 Pub Date:
 December 1988
 Bibcode:
 1988stun.proc..123A
 Keywords:

 Channel Flow;
 Flow Distribution;
 Flow Stability;
 NavierStokes Equation;
 Probability Density Functions;
 Turbulent Flow;
 Computational Fluid Dynamics;
 Stochastic Processes;
 Vortices;
 Fluid Mechanics and Heat Transfer