The patterning behaviour and accumulation of spherical particles in a vibrated non-isothermal liquid

Abstract

A completely new phenomenon of particle accumulation in vibrated non-isothermal monodisperse suspensions of solid spheres (in a liquid) is analyzed. For the first time evidence is provided for this case that even in situations in which particle-particle hydrodynamic interactions are negligible (dilute systems), intriguing nonlinear effects can lead to the irreversible formation of well-defined particulate structures over "long" temporal scales, i.e., times much larger than the period of the applied vibrations. The long-range translational ordering is produced by the delicate interplay between convective effects (of thermovibrational nature) and the (inertial) response of each isolated particle to the time-periodic acceleration. A new family of particle attractors in the physical space is identified with the topological dimension being essentially a function of the "symmetry properties" of the considered vibrated system and related geometrical constraints

On the formation and morphology of coherent particulate structures in non-isothermal enclosures subjected to rotating g-jitters

“…where dim t is the dimensional time and 2 b    g (b and  being the amplitude and angular frequency of vibrations, respectively). As reference geometric model we assume the classical cubic cavity already considered by Lappa 34,36 . The related physical domain has characteristic size L and, as shown in Fig.…”

On the transport, segregation, and dispersion of heavy and light particles interacting with rising thermal plumes

“…For the sake of consistency with earlier works addressing companion subjects [47][48][49][50][51][52][53] , as the characteristic time scale of the fluid flow, we consider:…”

“…These mechanism are made particularly complex by the fact that, in addition to being compressible, just as thermal convection (see, e.g., Lappa 46 ), particle dynamics are, in general, dissipative. Continuing our computational investigation (see, e.g., Refs [47][48][49][50][51][52][53] ) into this general area, in the present study (unlike earlier works, which considered synthetic flows, isotropic turbulence or other circumstances) we target expressly the case of particles interacting with thermal plumes in thermogravitational flow. An increased understanding of these processes (see, e.g., Gan et al, 54 ;…”

On the nature, formation and diversity of particulate coherent structures in microgravity conditions and their relevance to materials science and problems of astrophysical interest

“…η for a fixed density ratio) must be expected to decrease the extent of the final particle accumulation regions (Lappa 2014b).…”

“…A variety of particle accumulation structures is possible according to the relative direction of vibrations with respect to the walls. When the angle φ shown in figure 7 increases from 0 to π/4, the shape of the accumulation region evolves from a cylindrical surface to compact surfaces (a kind of irregular ovoids) passing through the intermediate stage of a conical surface, which might be the signature of some hidden analytic order underlying the formation and existence of such attractors in the physical space (Lappa 2014b).…”