Measurement Of The Entropy Current In Compressible Turbulence

Walter Goldburg, Professor of Physics, University of Pittsburgh
Mahesh Bandi, Experimental Soft Condensed Matter Physics, University of Pittsburgh
J. R. Cressman, George Mason University

The rate of change of the entropy current dS/dt is measured for a system of particles floating on the surface of a tank of water maintained in a turbulent steady state. Various aspects of this entropy current (a random variable) will be discussed, including (a) its steady-state value and (b) fluctuations about the mean. The mean value measurements yield information about the Lyapunov exponents of the floaters. The probability density of function of the entropy current is also obtained, enabling a severe test of the Fluctuation Theorem of Gallavotti, Cohen, and others.

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