Understanding the dynamics of particles in turbulent flow is important in
many environmental and industrial applications. In this paper, the statistics
of particle pair orientation is numerically studied in homogeneous isotropic
turbulent flow, with Taylor microscale Reynolds number of 300. It is shown that
the Kolmogorov scaling fails to predict the observed probability density
functions (PDFs) of the pair rotation rate and the higher order moments
accurately. Therefore, a multifractal formalism is derived in order to include
the intermittent behavior that is neglected in the Kolmogorov picture. The PDFs
of finding the pairs at a given angular velocity for small relative separations
reveals extreme events with stretched tails and high kurtosis values.
Additionally, The PDFs are found to be less intermittent and follow a
complementary error function distribution for larger separations.Comment: 16 pages, 3 figures, accepted for publication in European Journal of
Mechanics / B Fluid
