FM24_10474
XXI International Congress of Theoretical and Applied Mechanics
Warsaw, Poland, August 15-21, 2004

Stochastic Model of the Conditional Lagrangian Acceleration of a Fluid Particle in Developed Turbulence

A. K. Aringazin, M. I. Mazhitov
Department of Theoretical Physics, Institute for Basic Research, Eurasian National University, Kazakhstan


Various types of models have been recently suggested to fit the Lagrangian high-Re turbulence data by the groups at Cornell and ENS-Lyon, and DNS by Mordant et al., Yeung, and Gotoh and Fukayama. The random intensity of noise approach to the 1D Laval-Dubrulle-Nazarenko model, based on the Navier-Stokes equation, is used to describe Lagrangian acceleration of a fluid particle in developed turbulence. This leads to consideration of a nonlinear Langevin equation for the acceleration $a$ with coupled additive and multiplicative noises. The stationary PDF associated to this equation is calculated exactly for model white-in-time Gaussian noises. The additive noise intensity and the cross correlation are assumed to depend on velocity fluctuations $u$ in an exponential way. The resulting conditional acceleration PDF $P(a|u)$, variance, and mean are found to be in a good agreement with the recent high-precision Lagrangian data by Mordant, Crawford, and Bodenschatz (2003).



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