The dynamic clustering phenomenon in 2D, rapid granular, simple shear flows has been investigated for mixtures of different-sized, but equal-material-density particles via discrete element simulation. Several new characterizations provide physically meaningful analysis of the clustering phenomenon. A modified form of the radial distribution function gives rise to a new long-scale minimum, the location of which provides a clustering length scale. This length scale tends toward the average distance from the center of a clustered region to the center of a dilute region in the direction perpendicular to the known alignment of clusters in 2D simple shear flow systems. In addition to the inherent value of the clustering length scale, it also finds use in defining a Gaussian filter, whereby the discrete system is smoothed and average clustered- and dilute-region concentrations are calculated. Moreover, the temperatures of both regions are calculated by assessing fluctuating velocities of particles within the respective region.;Results pertain primarily to binary and continuous particle size distributions (Gaussian and lognormal), though the evaluation of monodisperse systems serves to illustrate the baseline behavior of the characterization techniques. Two primary questions are considered for systems containing multiple particle sizes: (1) What is the effect of the particle size distributions on the prominence of clusters? (2) Does preferential segregation of large or small species occur within the clustered regions? Results indicate that all investigated particle size distributions (binary, Gaussian, lognormal) behave similarly with respect to these questions. The prominence of clusters increases with an increased deviation from the monodisperse limit. Moreover, large particles tend preferentially toward the clustered regions, which exhibit lower temperatures than surrounding dilute regions. Such segregation toward low-temperature regions is consistent with the well-known tendency in steady-state systems for the segregation of large particles toward steady-state low temperature regions, in spite of the transient nature of the clustered regions and the pertinent temperature gradients in the current work.
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