Convection and segregation in fluidised granular systems exposed to two-dimensional vibration

Abstract

Convection and segregation in granular systems not only provide a rich phenomenology of scientifically interesting behaviours but are also crucial to numerous 'real-world' processes ranging from important and widely used industrial procedures to potentially cataclysmic geophysical phenomena. Simple, small-scale experimental or simulated test systems are often employed by researchers in order to gain an understanding of the fundamental physics underlying the behaviours of granular media. Such systems have been the subject of extensive research over several decades, with numerous system geometries and manners of producing excitation explored. Energy is commonly provided to granular assemblies through the application of vibration-the simplicity of the dynamical systems produced and the high degree of control afforded over their behaviour make vibrated granular beds a valuable canonical system by which to explore a diverse range of phenomena. Although a wide variety of vibrated systems have been explored in the existing literature, the vast majority are exposed to vibration along only a single spatial direction. In this paper, we study highly fluidised systems subjected to strong, multi-directional driving, providing a first insight into the dynamics and behaviours of these systems which may potentially hold valuable new information relevant to important industrial and natural processes. With a particular focus on the processes of convection and segregation, we analyse the various states and phase transitions exhibited by our system, detailing a number of previously unobserved dynamical phenomena and system states.

New Insight into Pseudo-Thermal Convection in Vibrofluidised Granular Systems

“…Rather, there exists a wide range of parameter space for which the frictionally-driven dense-convective mechanism and the dissipation-driven dilute-convective mechanism may be expected to coexist. Indeed, previous research 31 has shown the pseudo-thermal mechanism to be active even in decidedly dense ( ) systems. In spite of the presence of such a ‘crossover’ regime, it is nonetheless possible to ensure that the systems utilised here exist in an unequivocally dilute regime and hence exhibit solely pseudo-thermal convection, thus in turn ensuring that our results are clear and unambiguous in their interpretation.…”

Resuspension processes in a wide range of particle sizes

“…For larger grains ( 200 m), conditions for the initial destabilization of sand grains by the wind action are important to predict the transport of sandy matter in deserts [25]. Likewise, in granular matter manipulation stages, the mechanical collective vibration of grains, either horizontal or vertical, is also an important external perturbation giving rise to phenomena as segregation, convection cells, fluidization and many other interesting problems that have been extensively studied in the granular matter community [26][27][28][29][30][31][32][33][34][35].…”

Convection Rolls and Individual Particles Movements in Horizontally Vibrated Granular Particles System

“…Hysteresis of the transition explained through energy of collective movement of particles relative to the container [30]. Various states, phase transitions of processes of convection and segregation were analyzed by specifying the earlier unnoticed dynamical phenomena [31]. Mechanics behind the homogeneous and non-homogeneous convection in granular systems is important for scientists and engineers for industrial processes.…”