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

Abstract

The strategy undertaken in earlier author's work (M. Lappa, Phys. Fluids, 26(9), 093301, 2014; M. Lappa, Int. J. Multiphase Flow, 93: 71-83, 2017) based on the use of polarized (purely translational) vibrations for achieving the segregation or accumulation of solid particles in specific regions of an initially dilute dispersion is further pursued by allowing the direction of vibrations to change in time with respect to the applied temperature difference. In particular, the potential of the considered approach in separating the particles from the liquid is explored under the assumption that the angular velocity by which the vibrations axis rotates about a fixed axis is of the same order of magnitude or smaller (one or two orders of magnitude) than the frequency of shaking. A new family of particle coherent structures is identified in the physical space, which can be distinguished from the companion category of particle attractors for fixed vibration direction due to its increased symmetry properties. It is shown how the average nonlinear effects produced by the rotation of the vibration axis, together with those induced by the finite size of the enclosure, accumulate over time leading to the observed fascinating variety of symmetrical patterns.

Symmetry breaking phenomena in thermovibrationally driven particle accumulation structures

“…In line with our umbrella of on-going research on this subject 37,[53][54][55] , and given the success already enjoyed by this formulation in other parallel lines of research 2-3, [30][31][32]58 , we rely on a separate Lagrangian strategy to track particles. In particular, the need to account for particle inertial and drag effects (produced by the different density of particles with respect to the surrounding liquid and their non-infinitesimal size), is naturally dealt with through the so-called Maxey-Riley equation (see, e.g., Maxey and Riley 59 , Kuhlmann et al, 60 ), which in (dimensional) vector form reads:…”

“…Recently, a new category of particle attractors driven by joint (liquid) thermovibrational and (particle) inertial effects has been identified in closed cavities with various shapes and symmetries (Lappa [53][54][55] ). The present analysis aims to integrate the information reported in those studies by considering a previously overlooked aspect, that is, the steady velocity component that this type of convection can produce in some circumstances.…”

Particle accumulation structures in noncylindrical liquid bridges under microgravity conditions

“…Various fundamental types of particle-fluid interaction stemming from different situations in nature and technology are often regarded as archetypal systems for advancing our knowledge of complex fluids and multiphase flows [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. In such a context, the structures produced by the self-organization of particles have enjoyed a widespread interest over recent years as a classical workhorse to predict the nonlinear dynamics of these systems and their asymptotic behaviors.…”

On the influence of gravity on particle accumulation structures in high aspect-ratio liquid bridges

“…2011), thermocapillary (Melnikov & Shevtsova 2017; Gotoda et al. 2019) and thermovibrational convection (Lappa 2016 a , 2019).…”

“…It covers an extremely vast field encompassing different 'variants' such as particles transported by flows produced by pressure gradients (forced convection, see, e.g. Matas, Morris & Guazzelli 2003;Lashgari, Picano & Brandt 2015), differential rotation (Subbotin & Kozlov 2020) or induced by temperature gradients such as thermogravitational (Akbar, Rahman & Ghiaasiaan 2009;Puragliesi et al 2011), thermocapillary (Melnikov & Shevtsova 2017;Gotoda et al 2019) and thermovibrational convection (Lappa 2016a(Lappa , 2019.…”