@article{ISI:000426527300010,
 abstract = {We present an extensive numerical study of the time irreversibility of
the dynamics of heavy inertial particles in three-dimensional,
statistically homogeneous, and isotropic turbulent flows. We show that
the probability density function (PDF) of the increment, W(tau), of a
particle's energy over a time scale tau is non-Gaussian, and skewed
toward negative values. This implies that, on average, particles gain
energy over a period of time that is longer than the duration over which
they lose energy. We call this slow gain and fast loss. We find that the
third moment of W(tau) scales as tau(3) for small values of tau. We show
that the PDF of power-input p is negatively skewed too; we use this
skewness Ir as a measure of the time irreversibility and we demonstrate
that it increases sharply with the Stokes number St for small St; this
increase slows down at St similar or equal to 1. Furthermore, we obtain
the PDFs of t(+) and t(-), the times over which p has, respectively,
positive or negative signs, i.e., the particle gains or loses energy. We
obtain from these PDFs a direct and natural quantification of the slow
gain and fast loss of the energy of the particles, because these PDFs
possess exponential tails from which we infer the characteristic loss
and gain times t(loss) and t(gain), respectively, and we obtain t(loss)
< t(gain) for all the cases we have considered. Finally, we show that
the fast loss of energy occurs with greater probability in the
strain-dominated region than in the vortical one; in contrast, the slow
gain in the energy of the particles is equally likely in vortical or
strain-dominated regions of the flow.},
 article-number = {033102},
 author = {Bhatnagar, Akshay and Gupta, Anupam and Mitra, Dhrubaditya and Pandit,
Rahul},
 doi = {10.1103/PhysRevE.97.033102},
 eissn = {2470-0053},
 issn = {2470-0045},
 journal = {PHYSICAL REVIEW E},
 month = {MAR 2},
 number = {3},
 orcid-numbers = {Gupta, Anupam/0000-0002-7335-0584},
 researcherid-numbers = {Gupta, Anupam/N-4777-2018},
 times-cited = {6},
 title = {Heavy inertial particles in turbulent flows gain energy slowly but lose
it rapidly},
 unique-id = {ISI:000426527300010},
 volume = {97},
 year = {2018}
}