A dynamical equation for the distribution of a scalar advected by turbulence
نویسندگان
چکیده
A phenomenological model for the dissipation of scalar fluctuations due to the straining by the fluid motion is proposed in this Brief Communication. An explicit equation is obtained for the time evolution of the probability distribution function of a coarse-grained scalar concentration. The model relies on a self-convolution process. We first present this model in the Batchelor regime and then extend empirically our result to the turbulent case. This approach is finally compared with other models. © 2007 American Institute of Physics. DOI: 10.1063/1.2472506
منابع مشابه
Clustering of advected passive sliders on a fluctuating surface
We study the clustering properties of advected, noninteracting, passive scalar particles in a Burgers fluid with noise, a problem which maps to that of passive sliding particles moving under gravity on a surface evolving through the Kardar-Parisi-Zhang equation. Numerical simulations show that both the density-density correlation function and the single-site mass distribution scale with system ...
متن کاملDissipation Statistics of a Passive Scalar in a Multidimensional Smooth Flow
Intermittency and strong non-gaussianity of developed turbulence are most clearly reflected in the peculiar structure of the observed probability distribution functions (p.d.f.) of the gradients of the turbulent field. A typical logarithmic plot of the gradients p.d.f. is concave rather than convex, showing a strong central peak and slowly decaying tails. 2) Rare strong fluctuations are respons...
متن کاملSimulation of Low Reynolds Number Isotropic Turbulence Including the Passive Scalar
Full simulations of homogeneous isotropic turbulence containing a homogeneous passive scalar were made at low Reynolds numbers and various Prandtl numbers. The results show that the spectral behavior of the two fields are quite similar; both fields decay as power-law functions of time. However. the decay exponent is quite dependent on both the Reynolds and Prandtl numbers. The decay exponent of...
متن کاملMicroscale Complexity in the Ocean: Turbulence, Intermittency and Plankton Life
This contribution reviews the nonlinear stochastic properties of turbulent velocity and passive scalar intermittent fluctuations in Eulerian and Lagrangian turbulence. These properties are illustrated with original data sets of (i) velocity fluctuations collected in the field and in the laboratory, and (ii) temperature, salinity and in vivo fluorescence (a proxy of phytoplankton biomass, i.e. u...
متن کاملxx , Evolution of trajectory correlations in steady random
We analyze the behavior of the correlation for two nearby trajectories of motion in a random incompressible ow with nonzero mean and small uctuations. We show that the Fourier transform of the Richardson function of a passive scalar advected by the ow satisses, under certain conditions, a radiative transport equation. We also study the stretching of curves advected by the ow and show that their...
متن کامل