Kraichnan model of passive scalar advection

E183469

The Kraichnan model of passive scalar advection is a theoretical framework in turbulence that studies how a passively transported quantity (like temperature or pollutant concentration) evolves in a fluid flow modeled by a Gaussian, white-in-time random velocity field.

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Predicate Object
instanceOf stochastic partial differential equation model
theoretical model
turbulence model
allows closed equations for scalar correlation functions
exact or asymptotically exact scaling exponents in some regimes
appliesTo dye concentration as passive scalar
pollutant concentration as passive scalar
temperature fluctuations as passive scalar
assumes Gaussian velocity field
homogeneous velocity field statistics
incompressible velocity field
isotropic velocity field statistics
passive scalar does not affect the velocity field
statistical stationarity of the velocity field
white-in-time velocity statistics
characterizedBy Markovian time statistics of velocity field
scale-invariant spatial correlations of velocity field in inertial range
coreEquation advection-diffusion equation with random velocity field
describes evolution of a passively transported scalar field
field fluid dynamics
statistical physics
stochastic processes
turbulence theory
focusesOn higher-order scalar structure functions
statistical properties of passive scalar field
two-point correlation functions of passive scalar
frameworkFor comparison with direct numerical simulations of passive scalar transport
testing closure approximations in turbulence
testing renormalization group methods in turbulence
involves Fokker–Planck-type equations for probability densities
eddy diffusivity concepts
zero modes of correlation operators
namedAfter Robert Kraichnan
surface form: Robert H. Kraichnan
predicts multiscaling of passive scalar structure functions
relatedTo Eulerian description of turbulence
Kolmogorov spectrum of turbulence
surface form: Kolmogorov 1941 theory

Lagrangian description of turbulence
passive scalar turbulence
simplifies Navier–Stokes dynamics by prescribing velocity statistics
spatialCorrelation power-law dependence on separation in inertial range
studies passive scalar advection
transport of passive scalars in turbulent flows
timeCorrelation delta function in time for velocity field
usedFor analytical investigation of turbulent transport
study of anomalous scaling in turbulence
study of intermittency of passive scalars
usedIn theoretical studies of mixing and dispersion in fluids
uses Gaussian random field for velocity
delta-correlated-in-time velocity field

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Robert Kraichnan knownFor Kraichnan model of passive scalar advection
Robert Kraichnan hasNotableConcept Kraichnan model of passive scalar advection
this entity surface form: Kraichnan passive scalar model