The fluctuation theorem is a pivotal result of statistical physics. It
quantifies the probability of observing fluctuations which are in violation of
the second law of thermodynamics. More specifically, it quantifies the ratio of
the probabilities of observing entropy-producing and entropy-consuming
fluctuations measured over a finite volume and time span in terms of the rate
of entropy production in the system, the measurement volume and time. We study
the fluctuation theorem in computer simulations of planar shear flow. The
simulations are performed employing the method of multiparticle collision
dynamics which captures both thermal fluctuations and hydrodynamic
interactions. The main outcome of our analysis is that the fluctuation theorem
is verified at any averaging time provided that the measurement volume exhibits
a specific dependence on a hydrodynamic time scale.Comment: 4 pages, 3 figures, to appear on Physical Review Letter
