Test of the Fluctuation Relation in lagrangian turbulence on a free surface
نویسندگان
چکیده
Test of the Fluctuation Relation in lagrangian turbulence on a free surface. Abstract The statistics of velocity divergence are studied for an assembly of particles that float on a closed turbulent fluid. Under an appropriate definition of entropy, the two-dimensional lagrangian velocity divergence of a particle trajectory represents the local entropy rate ˙ S, a random variable in time. The statistics of this rate, measured in the lagrangian frame, are collected over a wide range of values. This permits a severe test of the fluctuation relation (FR) over a range that exceeds prior experiments, out to a regime beyond which the FR no longer holds. Notably, the probability density functions (PDF) of the dimensionless divergence σ τ are strongly non-gaussian.
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