[GTP] GTP MMM - Seminar at NCAR Thursday December 2, 2010

[Carolyn Mueller]

Turbulent mixing and beyond: problems, concepts, solutions

Snezhana I. Abarzhi

University of Chicago

Turbulent mixing plays an important role in a broad variety of natural 
and artificial systems, spanning astrophysical to atomistic scales and 
low to high energy densities. Examples include inertial confinement 
fusion, supernovae, atmospheric and oceanic convection, non-canonical 
boundary layers and optical free-space communications. Theoretical 
description of non-equilibrium mixing transports is a challenging 
problem due to singular aspects of the governing (Euler or 
Navier-Stokes) equations. Furthermore these processes are statistically 
unsteady and their fluctuating quantities are essentially time-dependent 
and non-Gaussian. We apply the new theoretical concept, the rate of 
momentum loss, to describe the transports of mass, momentum and energy 
in turbulent mixing flow and to capture its anisotropic and 
inhomogeneous character. It is shown that invariant, scaling and 
spectral properties of unsteady turbulent mixing differ substantially 
from those of isotropic and homogeneous turbulence. Time- and 
scale-invariance of the rate of momentum loss leads to non-dissipative 
momentum transfer, to 1/2 and 3/2 power-law scale-dependencies of the 
velocity and Reynolds number and to non-Kolmogorov spectra. Turbulent 
mixing exhibits more order compared to isotropic turbulence, and its 
viscous and dissipation scales are finite and set by flow acceleration. 
We describe the random character of the unsteady turbulent flow and show 
that the rate of momentum loss is the statistical invariant and a robust 
diagnostic parameter for either sustained or time-dependent 
acceleration. Some criteria are discussed for the estimate of the 
fidelity and information capacity of the experimental and numerical data 
sets.

December 2, 2010
FL2 main Auditorium
Room 1022
Lecture 3:30 pm

-- 
Carolyn Mueller
NCAR IMAGe
1850 Table Mesa Drive 
Boulder, CO 80305 
www.image.ucar.edu 
Tel: 303 497-2491
Fax: 303-497-2483